Taken from the Executive Summary: "This document describes work undertaken as part of the Wireless Emergency Alerts (WEA) Program, formerly known as Commercial Mobile Alert Service (CMAS), at The Johns Hopkins University Applied Physics Laboratory for the U.S. Department of Homeland Security Science and Technology Directorate (DHS S&T). A computer model was developed for the purposes of investigating WEA system performance under specific scenarios and to identify recommended enhancements. This report presents the modeling approach and the results of the simulations performed using the model. The results highlight potential improvements that should be considered by DHS and the Federal Emergency Management Agency (FEMA) in future iterations of WEA. A public alert and warning system like WEA has to be able to operate continuously despite possible extreme conditions (e.g., massive infrastructure damage, heavy network traffic, cyber attacks). Because it is not possible to generate these conditions for testing in a controlled environment, a WEA computer model was developed to simulate the transmission of alert messages from alert origination through delivery to a citizen's mobile device. This report presents an analysis of simulated system performance under a variety of conditions, including scenarios with extreme conditions."