The authors discuss the development of a testbed, called the distributed simulation and prototyping testbed (DSPT), to model variable-connectivity radio networks. The DSPT constitutes a software environment in which distributed simulation and prototyping models of radio communication and command and control systems can easily be built. The environment consists of four separate software packages: communication simulation, communication monitor, scenario update/controller, and prototype node. These four packages work together to form a single distributed simulation and prototyping facility for communication network studies. They relieve the user from the need to consider many of the details that must be handled to implement a distributed testbed. Each package is easily extensible and can be tailored to specific networks, scenarios, monitor views, and prototyping needs.>

The design of a packet radio network must reflect the operational requirements and environmental constraints to which it is subject. In this paper, we outline those features that distinguish the High Frequency (HF) Intra Task Force (ITF) Network from other packet radio networks, and we present a design concept for this network that encompasses organizational structure, waveform design, and channel access. Network survivability is achieved through the use of distributed network control and frequency hopping spread-spectrum signaling. We demonstrate how the execution of the fully distributed Linked Cluster Algorithm can enable a network to reconfigure itself when it is affected by connectivity changes such as those resulting from jamming. Additional resistance against jamming is provided by frequency hopping, which leads naturally to the use of code division mutiple access (CDMA) techniques that permit the simultaneous successful transmission by several users. Distributed algorithms that exploit CDMA properties have been developed to schedule contention-free transmissions for much of the channel access in this network. Contention-based channel access protocols can also be implemented in conjunction with the Linked Cluster network structure. The design concept presented in this paper provides a high degree of survivability and flexibility, to accommodate changing environmental conditions and user demands.

A new architecture for mobile radio networks, called the linked cluster architecture, is described, and methods for implementing this architecture using distributed control techniques are presented. We illustrate how fully distributed control methods can be combined with hierarchical control to create a network that is robust with respect to both node loss and connectivity changes. Two distributed algorithms are presented that deal with the formation and linkage of clusters and the activation of the network links. To study the performance of our network structuring algorithms, a simulation model was developed. The use of Simula to construct, software simulation tools is illustrated. Simulation results are shown for the example of a high frequency (HF) intratask force (ITF) communication network.

In this paper we consider the problem of organizing a set of mobile, radio-equipped nodes into a connected network. We require that a reliable structure be acquired and maintained in the face of arbitrary topological changes due to node motion and/or failure. We also require that such a structure be achieved without the use of a central controller. We propose and develop a self-starting, distributed algorithm that establishes and maintains such a connected architecture. This algorithm is especially suited to the needs of the HF Intra-Task Force (ITF) communication network, which is discussed in the paper.