Posts Tagged ‘unlicensed wireless devices’

Twenty-Five Years of Unlicensed Spread Spectrum

Monday, May 10th, 2010
Telesystems' ARLAN

The first commercial spread spectrum product, Telesystems' ARLAN, a radio LAN introduced in 1988. Source: FCC.

Today, the Wi-Fi Alliance and the Wireless Gigabit Alliance announced an enhancement to the current suite of 802.11 standards (Wi-Fi) which promises multi-gigabit wireless networking, in the 60 GHz frequency band.  The two associations expect that devices which have the new enhancement will be tri-band, also able to operate in the 2.4 and 5.8 GHz bands where Wi-Fi currently operates.

However, I am not sure if the Wi-Fi Alliance or the Wireless Gigabit Alliance realize the auspiciousness of the occasion of their announcement.  The announcement comes twenty-five years and one day after a much ignored FCC decision.  On May 9, 1985, FCC adopted rules which permitted the operation of spread spectrum systems in the ISM bands (902-928 MHz, 2.4-2.48 GHz and 5.725-5.85 GHz).  This rule change enabled the commercial rise of Wi-Fi, as well as so many other products and technologies take for granted today, such as Bluetooth, cordless phones, and baby monitors.

The FCC took this decision on its own initiative, rather than relying on requests for rule changes from the industries it regulates.  (In fact, many of the companies which initially opposed the rule change now earn millions of dollars of revenue from selling products that operate in these bands.)  One important person diving the FCC proceeding was national treasure Mike Marcus.  Marcus published a terrific account of the FCC proceeding in the journal info last year.  (I published in the same issue, and beat him out for best paper).  For his vision and insight in pushing the rule change through, Marcus was rewarded with nine years of exile to the outer Bureaus of the FCC.

Insight:  It never ceases to amaze me that a well-made decision can have exponential implications down the line.  Relying on the industry to tell the regulator can be helpful; however, this approach does not always serve the public interest.  In all instances, the regulator should exercise independent judgment.

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The Uncommon Unlicensed – A Licensed Commons

Wednesday, March 24th, 2010
My Marriage License

I received a license, and my property rights all turned to commons.

I recently read Kevin Werbach’s excellent article on the TV white spaces, The Wasteland (not to be confused with T.S. Eliot’s The Waste Land).   I shared some of my ideas on his article with Kevin, and after an email exchange I came to the conclusion that there is a significant challenge to the successful opening up of the TV white spaces.

Under the White Spaces order, any unlicensed device which will operate in the band has to query a database and obtain permission before it can start transmitting.  Kevin argues that the white spaces database is independent of spectrum policy.  While that might be true, the imposition of the database will certainly hold implications for spectrum policy.  When a white spaces device has to query a database and obtain permission before it can operate, it is, by definition, no longer an unlicensed device.  Rather, the regime is a licensed commons.  This grant of permission is in fact a form of a license, albeit a light one.

Let me digress for a second.  A license is a grant of permission to do something.  It affords the right to “verb a noun”.  With a license one may: drive a car, own a dog, (try to) catch a fish, marry the woman of his (or her, depending on the state) dreams, or emit radio energy into the ether.  A spectrum license is usually coupled with some expectation of interference protection, but not always. The FCC already has utilized a myriad of different license types, including license-by-rule, operator, class, station, and geographic.  (I detail several different license types in my 2004 TPRC paper, at pp. 9-16.)

In my 2006 law review on Personal Communications Services (PCS), I examine both the licensed and unlicensed version of PCS.   The licensed commons is one of the factors which killed the unlicensed version PCS.  For unlicensed PCS, the FCC created a regime under which unlicensed users had to get permission from a non-profit firm called UTAM before they could start using their unlicensed PCS devices.  In doing so, the FCC inadvertently delegated to UTAM the power to grant licenses.

Think of the poster child for the unlicensed regime – Wi-Fi.  I can turn on my Wi-Fi anytime, anywhere, and leave it on until Ron Coase’s cows come home from grazing on the commons.  No grant of permission is required to access the spectrum (emit RF energy).  Now, consider a white spaces device.  When it turns on, it has to access a database somewhere and get the Okay to start emitting RF energy.  This is a grant of permission and is a form of a license, although the FCC has made Google or whoever is running the database is now the de facto licensor.

A licensed commons can be a very good thing.  Ham radio and the interstate highway system are both licensed commons and have both been very successful.  So, this type of arrangement can work in practice; however, when the alternative is less restrictive, the licensed system will not be desirable.  The FCC’s Part 15 rules are the international gold standard for unlicensed (and licensed-exempt) operation.  They are the one area where U.S. communications policy still clearly stands head and shoulders above the rest of the world.  The reason the Part 15 rules work so well is that it is spectrum policy without the spectrum (mathematically, spectrum policy – spectrum = Part 15).  The rules simply consider what is the maximum amount of irradiated power which can be emitted by a device without an unacceptable probability of causing harmful interference.  It is a classic efficiency approach and should be the basis of all radio operations.

In order for the White Spaces Order to be successful must offer device manufacturer and device users more benefit than they could achieve by using the existing Part 15 rules.  Device manufacturers can make devices to operate under the less restrictive parts of the Part 15 rules (the U-NII and spread spectrum rules).  So, they never made any successful products for U-PCS.   The same will be true for the White Space rules.  In order for the White Space database system to work, it will have to offer greater flexibility, more power, wider tuning ranges, more suitable frequency bands, etc. than the current Part 15 rules allow.

Insight:  Should the band not deliver on its promise punditocracy on the ‘property rights’ side of the spectrum policy debate will say: “I told you so – unlicensed never works.”  The sad irony is that if the White Spaces rules fail to deliver, it will not be because it is an unlicensed regime, but because it is truly a licensed regime.  I told you so, first.

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Wi-Fi? Wi-Not?

Thursday, February 18th, 2010

In the past several weeks, there have been several news articles and blog posts about the possibility of Wi-Fi being a solution to congested mobile networks.  There was a piece in Total Telecom, one by Maggie Reardon, and one by Stephen Rayment for the FT.

The argument is that the widespread adoption of smart phones and mobile Internet has congested mobile wireless networks to the breaking point.  In order to alleviate congestion on their 3G or 4G network, carriers could offload traffic onto Wi-Fi networks (including those of other operators).  This would free up the carriers’ limited spectrum resources which they obtained at auction through the licensing process.  And, it could be done more cheaply than upgrading existing cell sites. (Dana Blankenhorn at ZDNet correctly points out the inconsistency of giving more spectrum to wireless carriers if unlicensed operation is the solution. It was not so long ago that wireless carriers were crying foul that all Wi-Fi networks such as the now defunct Cometa presented unfair competition because they had not spent billions to acquire their licenses at auction.)

Insight:  Integrating mobile networks with Wi-Fi is a good idea.  It is, however, not a new one.  At a conference nearly eight years ago at Columbia University and in the ensuing paper, I suggested that wireless carriers consider incorporating Wi-Fi into their networks.  My reasoning was not so much about load balancing as it was about market segmentation.  Complementing existing 3G networks with Wi-Fi would enable carriers to offer tiered services – a best efforts service and a better than best efforts service – charging different prices for both and increasing profitability.  I also suggested it would be possible to use spectrum not licensed to the carrier such as the spectrum which has been allocated to CB Radio,  GMRS, or FRS.  A 2003 FCC rule change would allow handsets cable of operating both on mobile networks and in these bands. In this way, carriers could offer services like push-to-talk or walkie-talkies without encumbering their already burdened spectrum and networks. Users would be able to speak directly to others in their area, even users on other carriers’ networks.  Alas, there was not much economic incentive for carriers to sell such handsets because it would reduce the mobile termination revenues which carriers charge one another (and eventually their subscribers) for completing calls over their networks.  However, with the balance of market power tipping away from networks and in favor of handset providers recently, it might be possible that we would see such enabled handsets in the next few years.

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Next Generation Spectrum Regulation

Wednesday, December 9th, 2009
Spectrum band plan created by price-guided mechanisms

Spectrum band plan created by price-guided mechanisms

Winston Churchill famously said, “democracy is the worst form of government except all the others that have been tried.”  Perhaps the same can be said of spectrum auctions.  Auction mechanisms have been used starting in New Zealand in 1994 to award spectrum licenses to those who have the highest monetary value. Spectrum auctions have generally been highly effective, with the occasional failure.

Despite their success, auctions have some notable drawbacks such as the so-called winners curse and the fact the up-front license fees require spectrum users to raise capital beyond the princely sums necessary to build a wireless network – a barrier to entry.  However, auctions are far better than the administrative processes which have been used for nearly a century to determine spectrum assignments.  Administrative decisions tend not to be economically efficient because the regulator has limited access to information which market participants would be more able to amass and utilize. There are also problems of political independence and of regulatory capture.

While auctions have been used to determine who gets spectrum rights, they have not really been used to determine the contours of those rights.  These contours are still determined through administrative decisions.

I have just completed a major study on next generation spectrum regulation which can serve as the basis for removing certain barriers to spectrum access, allowing more effective sharing and efficient allocations.

I can think of no reason why a properly designed auction could not determine not only who gets the spectrum rights, but what those rights are.  (Think of it this way: an auction on eBay for a car could determine not just who gets the car, but the color of the car and whether it comes with, say, leather seats or alloy wheels.)  I built a mathematical model of a next-generation spectrum auction using the Shannon-Hartley Theorem as a means modeling behavior by valuing the spectrum when considering the actions of other would-be users.  In my model bidders could express their demands for not just bandwidth, but power, modulation, underlay/interference, and other characteristics.  When I ran an MS Excel-based version of the model, the result was a mix of high and low power uses in the winning bids.  The low power bidders (similar to UWB spectral densities) could in a second round be aggregated into some form of licensed commons with the coordination protocol determined in that part of the auction.  The outcome would resemble a shared use or common arrangement where no one party controlled the spectrum.  However, the most interesting thing was that because bidders could obtain spectrum allocations that more closely fit their needs, more than 40% of the spectrum bandwidth available in the auction was left unsold.  This spectrum was valued by the market to be best allocated to either public sector use or even low- to mid-power unlicensed use.

Insight:  You cannot see, touch, taste, smell, or hear radio spectrum.  Spectrum is not a thing; it is an idea – a legal and engineering construct that explains a physical phenomenon and helps us arrange our behavior accordingly.  That fundamental physical phenomenon is the fact that when electromagnetic waves are: (1) harmonic in frequency; (2) incident in time; and (3) alight on the same reception device, the ability of those waves to be used as information carriers is degraded.  This deleterious effect is known to us as interference.  Without some form of intervention, it is impossible to exclude or limit the use of a common resource such as spectrum. Without exclusion, users consume the spectrum without regard to fact that their usage causes the deleterious effect of interference for other would-be users.  Policies which help to mitigate inference with the least amount of effort will be the most socially beneficial.

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TV White Spaces and the Tragedy of the Commons

Tuesday, July 29th, 2008

For more than nine decades, lawyers, engineers, and economists have argued that radio spectrum regulation is needed due to the fact that without some form of intervention, it is impossible to exclude or limit the use of a common resource such as spectrum.  Without exclusion, users consume the spectrum without regard to their usage’s impact on the benefits obtained by other would-be users.  They, therefore, tend to overuse the spectrum, causing interference to other users.  This reduction in social welfare due to overuse is referred to as the Tragedy of the Commons.However, we can now observe from the debate surrounding the TV White Spaces that the ability to exclude certain users is not sufficient to remedy the Tragedy of the Commons. A relatively small number of over-the-air TV households are able to use these spectrum bands without regard to the costs their use imposes on the rest of Americans.  Indeed, according to the most recent FCC statistics, in 2005 only about 14% (See Appendix B, Table B-1) of US TV households receive their TV over-the-air. The remaining 86% get no direct benefit from this spectrum.

The National Association of Broadcasters is now opposing tests the FCC is currently conducting which will measure the impact of unlicensed use of the White Spaces on digital TV reception. In order to protect digital TV receivers, potential White Space users must be excluded, and the NAB is throwing its weight around to ensure that outcome.  According to a quote from NAB spokesman Dennis Wharton, “We’re not going to be engaging in threats or anything, but about 70 members of Congress have already sent letters in expressing concern.” Well, as I wrote in a previous entry on Cool Stuff, at least one of those 70 letters is total bunk. Nonetheless, the cost to all of society of affording interference protection to this minority must also be considered.

Insight: If the NAB’s argument is accepted without scrutiny, the 14% of TV households will prevent the other 86% of US TV households (plus the TV-less households) from using those radio frequencies for broadband Internet, baby monitors, new forms of low-power broadcast, and other RCS (really cool stuff).  This lost benefit will not be compensated.  The exclusion of certain competing uses is necessary but not sufficient to ensure that society reaps the maximum benefit from the radio spectrum.  A means through which spectrum users can bear the costs they impose on others by excluding them is also necessary.

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White Space and Gray Matter

Tuesday, February 12th, 2008

Congressman Jerrold Nadler recently published an Op-Ed in the New York Times. His analysis is so off-the-mark, I felt compelled to respond.

I want to begin with some terminology. He describes the White Spaces as being the “intervals between television channel frequencies.” This could mean the geographic separation between grade contours, the guard bands, or even the blanking intervals in NTSC progressive interlace. At any rate, white spaces are “white” because at a given time and place the frequencies are not being used as carrier waves. If the spectrum is not being used then, by definition, there cannot be interference. And not just interference alone, but harmful interference is the statutory level of protection.Now I am not sure about the previous white space tests, as I lack the engineering experience to adequately review the opinions. But, I have see arguments suggesting the are conclusive and ones stating that they are not dispositive. Either way, technology will eventually overcome these issues. There are, however, more glaring failures of Rep. Nadler’s arguments.

“Microsoft, Google and others are asking permission to use white spaces — free of charge — for millions of unregulated and unlicensed devices for personal networking systems that they would like to sell, including P.D.A.’s, wireless broadband devices and even toys. These devices could disrupt the new digital TV signals that government and industry have spent so much time and money to promote.”

This is misleading by misstatement and by omission. Misstatement: unlicensed devices are not “unregulated”. Omission – the broadcasters did not pay for their spectrum either. Moreover, who cares what the broadcasters sunk costs might be. Suppose Google and Microsoft will spend more to develop more important technologies.

Rep. Nadler goes on to say, “And because these personal devices would be unregistered, there would be no effective way of recalling them or curtailing their use, much less assuring that standards were adhered to their manufacture.” If you read the FCC Part 2 and Part 15 rules you will find that this is dead wrong. When I was at the FCC, I spent a lot of time working on precisely this issue. Before any radio device, be it licensed, unlicensed, or licensed-by-rule, can be imported or marketed in the US, it must be certificated to comply with FCC standards. In addition, users of unlicensed devices have “no vested right to continued operation.” So, if in the future, the FCC decides that white spaces are best left white, it has the power to make operating these devices a crime. When Wi-Fi is outlawed, only outlaws will have Wi-Fi.

Further, without a single iota of economic evidence, Rep. Nadler values digital terrestrial TV over all other uses of the spectrum. Moreover, he values co-primary access according to his own wants and desires. It is a cute device when he argues for the protection of football games and Broadway musicals alike, but this too is misleading. Who is to say that a football game or Broadway show (both of which take place in large controlled Faraday cages) is more important than my wireless email?! I don’t like football, but I like email. How about public safety? I think that’s a better use of the white space. And, would it not be better public policy if we were helping “[l]ow-income households, the elderly and people living in multifamily buildings who don’t have cable service and rely on antenna systems” to get online with cheap unlicensed broadband access, and not to watch more TV?

Finally, if the Broadway star and star quarterback are counting on unfettered spectrum access (a concept whose time has come and gone) they should pay for that access. Otherwise, they should share the spectrum with the rest of us who get great value out of unlicensed use.  Both types of spectrum access will and must coexist in the future.  The future of spectrum policy will not be about “scarecity” or “interference” so much as it will be about coordination of use.

Insight: People, I cannot stress this enough, use your gray matter before you talk about the white space.

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