RFID can utilize different sensors for different purposes. It can be electronically linked to sensors such as light, vibration, and temperature, in addition to access, humidity and more. The problem, again, is that it lacks the capacity to report what is detects until it reaches a choke point where it's data can be read. Satellite-equipped containers can likewise utilize these sensors, but the benefit is that satellite systems can be programmed to transmit immediately what was detected, and also to send signals to make changes like temperature adjustments in the container as the need arises. Satellite applications even also allow for remote unlocking of the doors because of the variety of data that can be sent. Finally, satellite offers redundancies in notifying the user of problems encountered during the international movement of the container. An RFID user only knows something when and if the container reaches the point where RFID readers are installed.
Both RFID and satellite require hardware, and RFID and satellite require the installation of an antenna into the container. However, the use of RFID means costs of infrastructure acquisition, antennas for fixed sites, handheld transceivers, the people to use them, and maintenance. Certainly, there are notable expenses of installing any type of signal creating, sending and receiving device in a container in a manner which allows its electronics to be protected in the not-so-gentle world of global shipping. Those expenses and design challenges apply to both RFID and satellite container communicators, but once installed in the container, satellite costs are limited to the cost of message traffic since the rest of the technology is provided by established vendors in this market like Orbcomm, Iridium and others. Satellite message traffic typically involves short burst of data, and that traffic can be designed to occur only when needed, making satellite a less expensive proposition, especially when compared to the infrastructure, maintenance, handheld readers, and corresponding personnel costs needed for a large-scale cargo security RFID deployments.
In this writer's opinion, RFID connected to container interrogation should not even be allowed in U.S. ports. It actually could serve as the means to detonate an explosive device. Because of its radio frequency characteristics and the legal requirement to use a frequency established and mandated by government regulations, anyone who knows the frequency can design a dirty bomb to explode when the container is interrogated in the U.S. seaport, making an RFID security system in effect, the detonation trigger.
While there is risk of this in any communication system, satellite signals are not as susceptible to this type of usage. With satellite, the antenna in the container is tuned to the correct frequency range and constantly picks up signals from the satellite. The modem understands the message protocol and intelligently answers. The information is then transferred between the container unit or modem and the satellite. Due to the constant communication between modem and satellite, one has to be a lot smarter to use the signal. One has to understand the message protocol, be able to decipher it and then use it to trigger a device. The mere presence of a signal is not enough.
Satellite signals are unique to each container, ciphering and deciphering are required, and the satellite modem would have to be designed to accomplish this type of triggering, requiring the manufacturer of the unit to design it to trigger a specific device in a specific container.
With RFID, it is, however, possible to listen for the correct frequency signal and trigger a device based on the presence of such a signal. Such a signal will, for instance, be automatically present in a port when interrogating a container using RFID.
In summary, it's my opinion that RFID is inadequate in almost every way for the needs of global container security. Then, why do industry giants seem to be committed to it? Its use is certainly understandable for retail, warehouse controls, and in any situation where one can control infrastructure and location, but when we approach global supply chain security, the technology falls short. The GEs, Maersks, and IBMs of the world may have simply jumped prematurely on the RFID bandwagon and many of those companies now want the U.S. government to support their RFID investment that they have made. But the more one knows about global supply chain security, the more one has to accept the inevitable: The future of global container security is not RFID; it is satellite.