6. Analysis of the existing architecture of HF communication based on internet protocol access with reference to the above considered infrastructures

Aim of this Document is to show the state of the art of the existing architectures of HF communication from the network point of view. We have analyzed the existing techniques, focusing on those architectures considered useful for the future SWING system development. The organization of the document in three main sections has been achieved in order to comply with the three layer of the ISO OSI model of our interest: data, network and application.

Due to the nature of SWING system, layer 2 techniques are mostly described from the MAC point of view, even though examples of data management techniques are described in Section 2. Indeed, standards like STANAG 5066 and STANG 4538 are focused on the definition of rules for data packet handling. More interesting to our purpose are the several MAC techniques defined for HF communication. This deliverable is focused on two peculiar protocols, HFTP (High Frequency Token Protocol) and DCHF (Distributed Coordination for High Frequency radio). The analytical comparison between these techniques shown in Section 3 would be useful for the definition of SWING system requirements.

Regarding the Network Layer, we illustrated how HF networks are often fully connected. However, the HF channel can be an unreliable propagation medium, with significant packet loss rates and other environmental effects, leading to intermittent link outages and even network partitions. Although an exhaustive range of routing techniques designed for HF communications is not available in the open literature, we focused our analysis on two specific protocols: the Optimized Link State Routing (OLSR) protocol (an optimization of the classical link state routing algorithm) and the Wireless Address Resolution and Routing Protocol (WARRP) (an integrated address resolution and routing functionality). An analysis of these two protocols has been shown under several traffic conditions.

Finally, some typical applications for HF network have been discussed. Among them, we chose those considered most likely applicable in the foreseen SWING network.