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DARPA Looks To Adaptive Battlefield Wireless Nets
An anonymous reader passed us a NetworkWorld link about an effort at DARPA to succeed in combat through networking. The idea is to keep soldiers in a position of informational superiority through a tactical radio network that would 'link' everyone together on the battlefield. "Project WAND, for Wireless Adaptive Network Development, will exploit commercial radio components, rather than custom ones, and use a variety of software techniques and algorithms, many of them only just now emerging in mature form. These $500 walkie-talkie-size radios will form large-scale, peer-to-peer ad hoc nets, which can shift frequencies, sidestep interference, and handle a range of events that today completely disrupt wireless communications ... [right now] 'The average soldier on the ground doesn't have a radio,' says Jason Redi, principle scientist for BBN's network technologies group, and the man overseeing the software work. Radios are reserved for platoon and company commanders, in part because of their cost: typically $15,000 to $20,000 each, with vehicle-mounted radios reaching $80,000."
Wouldn't these new battlefield wireless networks give off a radio signal? Couldn't someone with the right equipment then deduce the position of any force using such equipment for a tactical advantage?
Libertarian Leaning Political Discussion Forum.
A large portion of that cost is making the radio conform to military specifications for ruggedness, reliability, extreme environmental conditions, etc. It has to work in all possible conditions and also be "soldier proof". You wouldn't believe the amount of abuse that they are subjected to. The manufacturer is making a reasonable profit, it's very expensive to design, build, and support mil-spec hardware. It's not the sort of business to go into if you want to get rich quick.
Mea navis aericumbens anguillis abundat
Frequency Hopping Spread Spectrum is the technology the GP was referring to rather than the broader term "encryption". While FHSS can and usually is considered a form of encription not all flowers are roses.
The benifit to FHSS is that both endpoints know the frequency list so they know which frequencies and what order they should be hopping through therefore it is seamless as long as both endpoints remain in synch.
There are two ways that devices synch up their frequency list. One is physical connection (e.g. a 900MHz FHSS cordless phone placed in the cradle will re-synchronise the "channel" list and, if additional encription is implemented, their encryption key). The second method is during the handshake, or initial connection period of the radio link, on a pre-defined static frequency the frequency list is transmitted, then subsequent transmissions are carried out on the specified frequencies. In this case an encryption key is usually used to prevent eavesdroppers from being able to collect and use this frequency list. A new frequency list can be transmitted after the initial connection is made and perodically updated to increase the security or reliability of the link if needed.
Now this appears to be background noise as only very small snippets of the conversation, often times digital and/or encrypted to futher obfuscate the transmission, will be transmitted on any given frequency. This means that the pieces that can be received on any given frequency are tiny spikes in the transmission which are clicks or pops and would not be discernable from the "noise".
FHSS has been in use for many, many years by everyone from civilians to ultra top secret government orginizations to both hide or "encrypt" the communications and to reduce the interferance of similar devices operating on the same frequency bands.
Hope that is helpful.