Routing, Network Coding and TCP Support for Wideband HF Communications

Abstract

High frequency (HF) communications provide beyond line-of-sight (BLoS) links for robust and reliable delivery of critical messages over long distances. HF communications suffer from low data rates and are susceptible to highly dynamic HF channel effects. Wideband HF (WBHF) communication technologies aim to support higher throughput rates that can be achieved with higher bandwidth. While there has been progress in the design of WBHF technologies at the physical layer, there is a lack of network and transport layer solutions that can support WBHF communications with improved end-to-end network performance in terms of throughput, reliability, delay, and overhead. First, a high-fidelity WBHF network simulator is presented to implement, test, and evaluate network protocols under realistic HF channel conditions that show unique characteristics compared to other spectrum bands. The WBHF network simulator runs real packet traffic with the real network protocol stack on virtual HF radios. The integrated HF channel simulator models long, intermediate, and short time-scale HF channel effects. Second, routing is combined with packet-level coding to support reliable communications for unicast and multicast traffic while limiting the need for end-to-end feedback messages. To support interoperability with transmission control protocol (TCP) applications, a performance-enhancing proxy (PEP) is used to improve the throughput achieved with TCP for WBHF communications. These network solutions are evaluated with the high-fidelity WBHF network simulator and their feasibility to improve the WBHF network performance is demonstrated.