A common problem in modern military communication networks is node discovery. In order to form a robust and efficient network each node needs to notify the network of its existence and, where security policies allow, to report its location. Furthermore, the process of fast and covert new node identification and recognition can help prevent friendly fire incidents. Once a network is established, new nodes often need to join the existing network, and they need a way to do this without compromising their own security, or the security of the network that they are joining. In addition, an established network requires a method of discovering the existence of another disjoint network that has migrated into communication range, so that a cross-link can be established between the networks in order to form a larger network. This process of nodes "discovering" each other is called <i>node discovery</i>, and this provides a capability that has many applications. A good node discovery scheme for military communication related applications has a number of properties including: fast and reliable network entry, covertness, secure and jam proof signaling, and range extension compared to the primary communications link itself. For the purposes of this paper the mechanism that provides node discovery will be called the Discovery Waveform. The Discovery Waveform has many applications such as terminal discovery for wireless communications, node discovery for establishing networking, and seemingly unrelated applications such as bursting time critical data.
Ubiquitous communications will be the next era in the evolving communications revolution. From the human perspective, access to information will be instantaneous and provide a revolution in services available to both the consumer and the warfighter. Services will be from the mundane - anytime, anywhere access to any movie ever made - to the vital - reliable and immediate access to the analyzed real-time video from the multi-spectral sensors scanning for snipers in the next block. In the former example, the services rely on a fixed infrastructure of networking devices housed in controlled environments and coupled to fixed terrestrial fiber backbones - in the latter, the services are derived from an agile and highly mobile ad-hoc backbone established in a matter of minutes by size, weight, and power-constrained platforms. This network must mitigate significant changes in the transmission media caused by millisecond-scale atmospheric temperature variations, the deployment of smoke, or the drifting of a cloud. It must mitigate against structural obscurations, jet wash, or incapacitation of a node. To maintain vital connectivity, the mobile backbone must be predictive and self-healing on both near-real-time and real-time time scales. The nodes of this network must be reconfigurable to mitigate intentional and environmental jammers, block attackers, and alleviate interoperability concerns caused by changing standards. The nodes must support multi-access of disparate waveform and protocols.