Joint Use of Guard Capacity and Multiconnectivity for Improved Session Continuity in Millimeter-Wave 5G NR Systems

The intermittent nature of millimeter wave (mmWave) links caused by human-body blockage is an intrinsic property of the 5G New Radio (NR) technology that may cause drops of sessions already accepted for service. To improve the session continuity, multiconnectivity and guard capacity mechanisms have been proposed recently. Multiconnectivity enables dynamic handover between multiple pre-established spatially-diverse links, while guard capacity reserves a fraction of radio resources for the already accepted sessions by ensuring that they will have sufficient provisions in case of link blockage. In this study, we combine the tools of queuing theory and stochastic geometry to develop a mathematical framework for capturing the joint operation of these two schemes as well as the features of mmWave radio propagation. The metrics are related to user-and system-centric performance including the system resource utilization and the new and ongoing session drop probabilities. Our results show that multiconnectivity benefits all of the considered parameters. However, the range of performance boost remains limited by the deployment density and the maximum supported degree of multiconnectivity. In its turn, guard capacity allows to further decrease the ongoing session drop probability at the expense of the new session drop probability and the system resource utilization. When implemented jointly with multiconnectivity, guard capacity does not produce noticeable negative effects on the system resource utilization as compared to its standalone use. Hence, one may prefer a joint implementation of these mechanisms for preserving the session continuity of users without compromising the resource utilization.