Analyzing Handover Performances of Mobility Management Protocols in Ultra-dense Networks

To deal with the exponential increase of mobile data traffic, ultra-dense network (UDN) has been evolved as a promising solution for the forthcoming fifth generation (5G) cellular networks. In UDN, a mobile terminal (MT) experiences frequent handovers due to limited coverage regions of the deployed small cells. Such frequent handovers cause increased packet loss and blocking rate if the handover latency is very high. The handover latency explicitly depends on the layer 3 handover mechanisms of upper layer mobility management protocols (MMPs) as well as handover execution mechanisms (HEMs) operating at layer 2. The HEMs also have significant impact on layer 3 handover latency. Despite such dependencies, existing handover performance evaluations of MMPs do not adequately consider the effect of HEMs. In this work, we analyze the handover performances of different class of MMPs considering the effect of underlying HEMs in terms of handover latency, handover packet loss and handover blocking rate. For analysis purpose, we consider a network layer MMP namely fast mobile IPv6, a transport layer MMP namely seamless IP diversity based generalized mobility architecture, and a distributed mobility management protocol as candidate MMPs. Here hard and semisoft handovers have been considered as underlying HEMs. Our analysis reveal the conditional effect of underlying HEMs on the handover performances of upper layer MMPs. Further, based on such analysis, we prioritize among different combinations of MMPs and HEMs employing analytic hierarchy process. Such priority assignment would serve as a protocol selector in UDN scenario.