Wireless Systems Design

Wireless-Monitoring Solution Guards Ports

Today, a great deal of media attention is focused on the vulnerability of U.S. ports. Aside from a lack of personnel and financial resources, the port authorities are faced with a huge number of containers to inspect. Thankfully, it appears that wireless monitoring may now do much of the job for them.

To help cargo carriers comply with pending Homeland Security regulations, Ember Corp. (www.ember.com) and RAE Systems (www.RAESystems.com) have created and demonstrated a prototype wireless-security monitoring system. This system is designed to prevent terrorists from smuggling nuclear and other catastrophic weapons through American ports. Seven million shipping containers pass through those ports every year.

At the roots of the monitoring system are RAE Systems' hazardous environment sensors, dubbed RAEWatch. Those sensors have been enabled with Ember's wireless embedded RF chips and EmberNet networking software. Ember's radio chips, networking software, and network-management tools use a flexible mesh routing algorithm (see figure). They vow to create self-organizing and self-healing networks with very low power requirements and no single point of failure.

The resulting system wraps cargo in a mesh network "web" that detects weapons materials. It also details when containers have been opened and sealed and when contents have been removed or added. If a container was tampered with, information will be given to the port authorities.

This prototype made a timely entrance. Last November, the U.S. Department of Homeland Security stated its desire for all cargo companies shipping to American ports to equip their containers with wireless sensors. The department will give preferential treatment to "smart" containers. "Dumb" containers will have to go through slow, expensive manual inspections.

The RAEWatch sensors yield a node-to-node communication range with a reliable maximum nodal separation of ~30 m. Transmitting information over a larger distance requires network transmission.

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