Using physical layer emulation to optimize and evaluate mobile and wireless systems

Testing and evaluating protocols and applications for wireless networks and mobile users is challenging because the physical environment has a significant impact on the behavior and dynamics of the system. It is however important that these physical world effects are considered during system implementation and evaluation to ensure correct and efficient operation. Unfortunately, since these physical world effects are hard to control and model, this adds considerable complexity to system development. In this paper we show how a wireless networking testbed based on signal propagation emulation was used in the development, testing, and evaluation of mobile systems. The paper is organized as two case studies at different levels of the system: roaming in 802.11 networks and video streaming. We found that the combination of realism and control improved both efficiency and performance during development.