Hard Real-Time wireless communication in the northern Pierre Auger Observatory

The Pierre Auger Cosmic Ray Observatory employs a large array of Surface Detector stations to detect the secondary particle showers generated by the arrivals of Ultra High Energy Cosmic Rays. The operational Auger South site uses a tower-based wireless network for communication between the stations and observatory campus. Plans for a larger Auger North array call for a similar system. However, a variety of factors have rendered direct station-to-tower routing infeasible in Auger North. Thus, it will employ a new paradigm, the Wireless Architecture for Hard Real-Time Embedded Networks (WAHREN) designed specifically for highly reliable message delivery over a fixed network, under hard real-time deadlines. This paper describes the WAHREN topology and protocols, as well as real-time performance evaluation, formal verification, testbed operation, and Markov reliability modeling. The status of system hardware development and an on-site Research and Development Array are also discussed.