08.11.08

Quick Links 08/11/08

Posted in conferences, quick links, research initiatives, white space at 10:36 am by JamesNeel

First, contrasting viewpoints on white space testing:

(link) From Shure (after the Redskins / BIlls test):

“The FCC’s tests of prototype white space devices at FedEx field prior to Saturday’s game between the Redskins and the Bills conclusively show that spectrum sensing white space devices will cause harmful interference to wireless microphones during live events. Simply stated, the prototype devices were unable to consistently identify operating wireless microphones or distinguish occupied from unoccupied TV channels. More troubling, the devices failed to detect the presence of wireless microphones when switched on – an occurrence that takes place multiple times during any NFL game.

(link) From Motorola:

In an interview yesterday with FierceWireless, Steve Sharkey, Motorola’s senior director, regulatory and spectrum policy, said that the FCC has just finished most of the outdoor white space device testing and that Motorola’s white space device did very well in the tests. Sharkey said that Motorola uses geolocation technology, which means it uses a combination of location technology (such as GPS) and a database that advises the device on what channel to use and whether or not there is compatibility with other white space devices.”The geolocation approach has proved highly reliable,” Sharkey says.

(link) And Verizon wants white space devices licensed:

“Generally we have favored licensed spectrum,” Tauke said at a press conference, “but we are continuing to look at what the potential may be here.” On the other hand, he said he wanted to be certain that these applications, currently being evaluated by the FCC, don’t interfere with Verizon wireless products or anything else. “Nobody has passed the test” just yet, Tauke said.

My two cents. Applying these sorts of political slants to what should be a purely technical assessment (I have no first hand knowledge of the testing and no particular dog in the fight, but it seems to me they can’t all be right on the assessment) is inherent to decisions related to public goods and is a reason (among many) why I wish we would start transitioning to a regulatory regime that more closely mimicked private property.

(link) Effectively the same Motorola story as above, but this link has a line I want to discuss further.

Sharkey calls the tech “absolute, solid protection,” which should make members of the white space coalition happy — though we haven’t heard positive word from Philips, Adaptrum and InfoComm yet, who were also testing devices alongside Motorola, but aren’t using the geolocation technology. That, and the FCC has the final word on all of this, so we’ll just have to wait for that word from on high before we start riotous, interference free partying in the streets

The emphasis was in the original. There was a paper submitted to DySPAN that I wanted accepted (though not a very good paper and not anyone’s I know so ’twas rejected) which unwittingly made what I think is an important point – if 1) a primary user is turning off and on at unpredefined times and 2) is not helping secondary users (via a beacon or via any other method), then 3) secondary users will have to detect the presence of the primary when it starts transmitting. This then means that you simply can’t have assurances of interference-free operation if you want the secondary system to have any sort of useful throughput.

In practice, this means if we are constrained to detecting wireless mics via detection methods only, we will not be able to guarantee interference-free operation.

On a related note, I think IEEE USA did a real disservice to cognitive radio with their advocacy as it sets up the technology to fail by suggesting an impractical condition is inherent to the concept of cognitive radio.

By definition, CRs should be inherently non-interfering on a completely independent basis.

(link) Keith has done a valuable service and posted site measurements as matlab files on the DySPAN conference site for any researcher to use (mmm… real data). Unfortunately the DySPAN site appears to be down at the moment, so do check back later on this link. *Update* Here’s a direct link (zip).

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