Sandia labs demo ultrasecure wireless

'Simpler is better, smaller is better, lighter is better, less power consumption is better. You get all those with ultra-wideband.' ' Sandia labs' H. Timothy Cooley

'This is huge.' Sandia researcher H. Timothy Cooley demonstrates an ultrawideband wireless communication device using advanced government encryption.

Encrypting low-power, ultrawideband transmissions could have many uses for government agencies.

Researchers at the Energy Department's Sandia National Laboratories have demonstrated how to use a new wireless signal propagation technique called ultrawideband, or UWB, to convey secure information.

'We wanted to develop a super-secure wireless network,' said H. Timothy Cooley, senior scientific engineer at Sandia. The lab's prototype system demonstrated how UWB could be suited for secured low-powered sensor networks. 'The role of Sandia was to spearhead the development, [to] pull together the different pieces of that technology,' he said.

UWB promises to provide yet another format for transmitting data wirelessly. Born from work funded a decade ago by the Defense Advanced Research Projects Agency, this type of signal has several attributes that set it apart from WiFi, land radio and the signal formats used by cellular phone carriers. It requires very little power and can operate in environments rife with radio frequency disturbances.

Although still emerging in the marketplace, UWB has a range of possible uses, said Jon Adams, president of the UWB Forum. The UWB Forum, an industry and academic coalition, chiefly markets UWB as a way to eliminate the cables that connect electronic devices, such as computers, printers, stereos and televisions. To this end, the Bluetooth development bodies are looking at ways to use UWB to carry signals. But it can also be used as the signal for radio frequency identification tags. Today's UWB chip sets can produce a raw throughput from 100 Mbps to as much 2 Gbps, over distances as great as 100 meters.

Testing UWB for government

Vendors are in the early stages of designing and marketing UWB products, but Sandia wanted to see how the new propagation method could work for government agencies. The Air Force Electronic Systems Center sponsored the work. Chip set manufacturer Time Domain Corp. of Huntsville, Ala., provided its PulsOn chip set-based ultra-wideband radios for the project. Authentication tool provider KoolSpan Inc. of North Bethesda, Md., provided the test facilities and the SecurBridge encryption and decryption units.

For the test, a surveillance camera and thermal imager, supplying video streams, were connected to a video server. The server passed along the videos to the hardware encryption block, which encrypted the material using the 256-bit Advanced Encryption Standard and forwarded it to a UWB transmitter. The signal was then transmitted 100 yards to a UWB receiver hooked to a decryption unit. With real-time encryption in place, the system achieved a throughput of 1 Mbps.

'This is huge,' Adams said of the tests. Adams worked as an engineer for two decades at the NASA's Jet Propulsion Laboratory. At NASA, he saw a lot of military interest in setting up sensor networks using nodes that required very little power yet could transmit signals that were hard to pinpoint, disrupt or intercept. Sandia's demonstration excelled in these requirements.

'In many DOD and DOE applications, simpler is better, smaller is better, lighter is better, less power consumption is better. You get all of those with ultrawideband,' Cooley said.

In Sandia's test, the transmission required an average of 50 microwatts, a thousandfold decrease in the power needed for a WiFi transmission, which averages about 50 milliwatts, Cooley said.

UWB differs from most radio signal formats in that the signal is not modulated onto waveforms tailored for narrow frequencies. Ultrawideband signals are small pulses of energy, averaging about 100 picoseconds each, that are spread across a wide swath of spectrum, hence the descriptive 'ultrawideband.' A digital signal is transmitted by staggering the expected cadence of the pulses. Since UWB does not require frequency conversion, UWB transmitters do not need power-hungry digital signal processors. Nor do they draw energy to generate a waveform when no signal is present.

Such a decrease in power requirements can lead to a lot of possible uses previously thought impossible. For instance, a simple UWB communication device could transmit for 6,000 hours using a 1-volt (300mAh) battery, whereas a WiFi transmission would zap the battery's entire capacity in six hours. Of course, additional power would be needed to run the various sensors themselves.

Possible applications

Such efficiency could open the possibility, for instance, of placing transmitters on individual soldiers that could transmit their whereabouts and status of their health back, through local connection points, to command centers, Cooley said.
The low power would also be advantageous to the Energy Department, Cooley said. Sensors could be placed around nuclear facilities to keep tabs on conditions in places where higher-powered transmissions might destabilize dangerous materials.
Security could also be another major selling point for UWB. UWB works particularly well in what Cooley calls 'toxic RF environments,' in which there are many radio signals present along with severe interference and attempts to jam those signals. Thanks to the GHz-wide spread of its signal, UWB operates under this RF noise. The spread also makes it hard to pinpoint where signals originate, a useful security measure.

Sandia's idea was to augment UWB's natural ability to obscure the origin of its signals with the use of AES, the encryption standard used by government agencies. 'Our strategy was to combine the highly secure layer of UWB with the highly protective AES,' Cooley said.

For the test system, the transmission used the Internet protocol, which broke the stream into small datagrams. The encryption device used rotating 256-bit encryption keys. Each packet was encrypted with a different key, a technique that would make it practically impossible for eavesdroppers to reconstruct an entire message, given the sheer number of keys to crack.

'The combination of very low probability of intercept plus a robust encryption method make ultrawideband systems incredibly challenging to find and extract information from'if you're not the person who should be doing that,' Adams said. n

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