Broadcasters Plan Distributed-Denial-Of-Service Attack on White Spaces
Broadcasters Plan Distributed-Denial-Of-Service Attack on White Spaces
Broadcasters Plan Distributed-Denial-Of-Service Attack on White Spaces

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    The official agenda for the FCC’s September Open Meeting on Thursday lists the broadcast white spaces as one of the items.  This Order will resolve the details left hanging from the 2008 Order (although it now appears that it will not select the database operator), finally allowing development of this technology and forming the foundation for the next generation of unlicensed wireless technology.

    Or maybe not.  Even more than usual, this Order relies on getting all the details right. The limitations and interference mitigation mechanisms have left very little in the way of useable spectrum in the largest urban markets most attractive to manufacturers. Lose what’s left and you lose national markets necessary to interest developers and achieve economies of scale. Do anything further to drive up cost of manufacture or add a new layer of uncertainty and would-be developers – who have already been at this for [8 years] and poured millions of dollars into prototypes and pilot projects – will likely pull the plug and walk away. Anyone who remembers such promising technologies as ultrawideband and the resistance to it by incumbents should recognize the death by a thousand cuts approach favored by the broadcasters here.

    Allow me to select one example out of many to illustrate how a seemingly harmless little change in some small technical rule makes the difference between a viable service and something too expensive to develop profitably.  Under the rules established in 2008, we have a database that keeps track of what channels are available. A low-power mobile device can either operate in “Mode 2,” which means that it can independently contact the database. Or it can operate in “Mode 1,” which means that it check with a Mode 2 device or fixed base station to find out what channels are available.  I refer to this as a “ping,” because it is reminiscent of the ping function used by routers to rout packets based on the domain name system.

    Right now, the rules require a Mode 2 (the ones that access the database directly) to ping the database every 24 hours. Mode 1 devices “listen” to Mode 2, according to the 2008 Order (which I understand means “get told when an actual change occurs).  The broadcasters want the Mode 1 devices to ping the Mode 2s every 60 seconds and want Mode 2 to ping the database every 15 minutes, if not more frequently.  Since television broadcast towers are big stationary things, not Ents marching on Isengard, one may ask why devices need to check more than once a day. Apparently, broadcasters imagine that some news team running down the street after some hot news lead might slam into someone using a smart phone with white spaces capability.

    So what is the harm with guarding against such an unlikely scenario by mandating check-ins once a minute/every 15 minutes for Mode 1/Mode 2 devices? Lets work it out. There are 1,440 minutes in a day. So every Mode 1 device will go from “listening” to a Mode 2 device to pinging the Mode 2 device 1,440 times a day. Meanwhile, Mode 2 devices will go from pinging the network once every 24 hours to 96 times every 24 hours.

    That’s quite a load change.  Sure, it’s a low-power ping. But multiply something low-power by 1,440 times and it starts to add up. For the Mode 1 devices, it becomes a serious battery killer. For the Mode 2 “server” devices, however, the destructive consequences increase exponentially for every Mode 1 “client.” On one end, rather than having Mode 1 devices listen, it must devote processing time and power to answer the same question 1,440 times a day. For every new device added, it increases the workload by 1,440 times. On the back end, the Mode 2 device must also ping the database every 15 minutes, increasing the total number of database pings from 1 every 24 hours to 96 times every 24 hours.

    At best, this increases costs throughout the entire system to the point where it threatens the viability of the technology. That’s a heck of a cost to pay “just to be safe” so that some random mobile news crew of the future doesn’t experience a minor burst of interference and deprive us of Lindsey Lohan’s next brilliant utterance.  But more likely this “minor change” causes the system to collapse under the increased demand. Remember for the Mode 2 devices, this is a synchronized ping from all devices coming in at 60 second intervals, which multiplies by 1.440 times per day for every new device that turns on.

    Those familiar with network security may recognize this as strikingly similar to a “distributed denial of service” attack.  The hacker attacking the network causes the client to ping the server for routing information repeatedly, and from an increasing number of devices, until the system becomes overloaded. The same dynamic comes into play here. Except that instead of being planted in the system by a malicious hacker, this gets planted in the network by well-meaning FCC Commissioners at the insistence of broadcasters who have spent the last 8 years trying to convince anyone gullible enough that white spaces means the end of broadcast television.  Lest you think I exaggerate in the heat of advocacy rhetoric, I invite you to review this “educational” film, Your Neighbor’s Static, pushed out by the broadcasters to persuade regulators and the public that if you approve white spaces devices poor Grandma will not be able to watch her programs because of the interference from mean old Mr. Google and Ms. Microsoft running their nasty interfering white spaces devices next door.

    The FCC absolutely needs to get this right, and get it right now. Developers have hung on for 8 years, in the face of endless testing designed to address the criticisms from incumbents with every interest in remaining unsatisfied. For the last two years, developers, the FCC, and the NTIA have looked to the white spaces architecture as providing the next generation of innovation for unlicensed technology. If we blow it here, odds are good that the companies looking to develop this technology in the United States will roll their eyes and head for other countries, like China or Brazil, that want to get serious about new wireless technologies.