Adaptive data delivery over disadvantaged, dynamic networks

Most applications and network protocols are designed under the assumption of a stable and consistent physical network infrastructure. However, the communications infrastructures of most military tactical networks are dynamic and dependent on mission CONOPS and network topology. Further, they are highly variable in their capabilities from one data link to the next. Consequently, it is difficult for standard applications and services to maintain reliable quality of service when transiting to a dynamic tactical network, or crossing the borders between different classes of military networks. Ultimately, this lack of network awareness impacts the quality and timeliness of actionable intelligence delivered to the warfighter. General Dynamics and the Naval Research Laboratory (NRL) have collaborated on efforts to improve the reliable delivery of live video data across these disadvantaged tactical networks. We address the development of a network-aware video server, which senses network characteristics and dynamically transcodes video to meet the capacity of network between the server and clients. End-to-end network characteristics are required to drive the video transcoder. These network attributes can either be derived from software methods by analyzing the network protocol, or using specialized network hardware (e.g. tactical radios, routers, or QoS devices). For this effort end-to-end network awareness was collected from the NACKOriented Reliable Multicast (NORM) [1] protocol operation. Hooks in the NORM protocol provide a network information service with access to path bandwidth, delay, and lost packets. The video server uses the network information service to adapt the video by adjusting frame size, frame rate, and compression according to current network conditions to deliver the video with minimal delay. A comparison of how video is streamed over enterprise networks and the improved delivery methods made by General Dynamics and NRL for tactical networks is presented.