Wireless network emulation for distributed processing systems

A formidable challenge for laboratory integration and testing of a wireless distributed processing system is establishing a representative wireless network for data communications. Realistic network performance is particularly necessary when system operation is sensitive to the throughput, delay, and reliability characteristics of a low-bandwidth ad hoc network. When the processing node data interfaces are actually radios with embedded networking protocols, the space, environmental, and logistics constraints of laboratory hardware-in-the-loop component testing require emulating the performance of the wireless radio network. The unrealistic alternative to full-scale RF network emulation in the laboratory is to take developmental equipment into the field and attempt to debug any functional or performance anomalies using the target radio network. This paper describes an approach for integrating and testing wireless systems in the laboratory with real-time emulation of ad hoc radio networks. A wireless emulator in this paper is capable of modeling all levels of the network protocol stack and many characteristics of the physical RF layer, including propagation losses, co-channel interference, and bit error rates. Earlier in the system development cycle, the same communications emulator supports software simulations for requirements analysis and system design. With compatible simulations and emulations, system development can progress naturally through functional design, system simulation, node prototyping, and distributed system integration, to field demonstrations with the actual RF network.