Modeling and Analysis of Multi-RAT Dual Connectivity Operations in 5G Networks

Multi-Radio Access Technology (multi-RAT) dual connectivity (DC) is an important feature in the 3rd Generation Partnership Project (3GPP) fifth generation (5G) New Radio (NR) specification. This feature aims at providing better throughput, latency and mobility performance for the end user by augmenting existing Long-Term Evolution (LTE) infrastructure with the new 5G NR base stations. In this paper, we develop a simple analytical model that captures the relevant characteristics of this tightly coupled network. Using the model, we investigate the level of traffic steering and flow control required for the system to achieve its full potential for a variety of operating conditions. We present a non-exhaustive set of numerical results from the model that provide insight into the complex interplay between packet delay experienced at the user equipment and system parameters such as LTE and 5G link capacities, user traffic demands, and 5G link dynamics. Our results indicate that dynamic flow control and traffic steering mechanisms that can quickly respond to varying network conditions are critical to achieving low latency, high user data rates, and increased reliability that are often attributed to the 5G technology.