Dynamic Adaptation of the User Data Flow to the Changing Data Rates in VHF Networks: An Exploratory Study

The adaptation of tactical systems to either message outbursts of user-behavior or unpredictable network changes is a necessary condition to guarantee the robustness of the system. However, both events are likely to occur simultaneously in military scenarios, in case of which the system can use multilayer control loops to adapt its store-and-forward mechanism. This paper is a part of a wide investigation to evaluate the robustness and solve the related issues of tactical systems. Our architecture implements the store-and-forward mechanism with a hierarchical queuing model of the message, IP packet, and radio buffer. In this study, we want to solve the data overflow in memory -constrained devices such as radio buffer caused due to data outbursts, eventually, leading to packet loss. In order to mitigate radio buffer overflow, we introduce a control point to dequeue the packets from the packet handler to the radio buffer. Our system adds an Inter- Packet- Interval (IPI) to control the admission into the radio buffer. IPI is computed using the nominal link data rate compiled by the radio together with buffer metrics such as the occupancy and threshold. We discuss experimental results from a VHF network suggesting that our cross-layer IPI allows better control of the buffer usage thereby increasing the system robustness to ever-changing link data rates in the network.