Redundant wireless communication technologies for real-time surveillance

Catastrophic events including those sparked by terrorism have cast a pall over society in recent years. Events such as September 11th or the bombing of the Alfred P. Murrah Federal Building in Okalahoma City demonstrated a sudden surge in telephone call volume. These events indicated that communications systems, including cellular, can fail as a result from damage or capacity overload. Cellular systems have significant capacity given the limited radio spectrum allocated but much like airlines that oversell seats because inevitably some passengers do not show up, cellular providers typically have more customers than operational spectrum can handle in aggregate. Normally this is perfectly acceptable because a high percentage of the customer base would never be making calls simultaneously; except in an emergency. Such emergencies can be active or passive in nature. The release of dangerous airborne agents is one such scenario. The purpose of this study was to use a portable air particulate sensor as a data acquisition platform to evaluate the capability of real-time data throughput using existing wireless topologies, Java, eXtensible Markup Language (XML) and Internet protocols when cellular transmission frequencies are compromised. Results show that high levels of cellular voice traffic in a given area can hamper simultaneous data communications; however, Low Earth Orbiting Satellites (LEOS) can provide redundancy.