Efficient Handover Mechanisms for Heterogeneous Networks

Abstract

In this thesis, some analytical frameworks have been developed to analyze the effect of different system parameters on handover performances in heterogeneous net-work (HetNet) and based on such frameworks, some efficient handover algorithmshave been proposed. The study starts with an analytical framework to investigate the effect of resource allocation mechanisms, upper layer resource allocation mechanisms(MMPs) and handover decision metrics on user perceived throughput. This analysis re-veals that among other factors, handover decision metric plays a crucial role in deter-mining user perceived throughput inHetNet. Subsequently, we develop two handover decision metrics for ultra dense networks (UDN) and unlicensed band communicationsspecifically. For UDN scenario, a handover mechanism has been developed to deal withthe period of time prior to handover initiation when a mobile terminal (MT) is connectedto the serving cell but not getting the requested data rate. In unlicensed band commu-nication, channel conditions mayfluctuate drastically due to the interference caused bythe co-existence of several networks in unlicensed band. For such a scenario, a han-dover mechanism has been proposed to select the optimal target network from a set ofcandidate networks. To provide seamless connectivity in HetNet, dual connectivity(DC) and separation between control and user planes have been emerged as promisingsolutions. An analytical framework has been developed to investigate the performanceofDC in control-user plane splitHetNet explicitly considering the data rate demandsof theMTs, traffic arrival pattern and channel conditions. Finally, we analyze the han-dover performances of different classes ofMMPs considering the effect of underlyinghandover execution mechanisms such as hard and semisoft. Based on this analysis, dif-ferent combinations ofMMPs and handover execution mechanisms have been prioritizedusing analytic hierarchy process. The significance of the developed analytical frame-works lie in the fact that these analyses would provide deeper insight towards serviceguarantee and system design inHetNet.