Unfortunately, You Can't Make

the Wireless Microphone

Problem Go

Away by Taking a Different

Tack in TV White Spaces

There seem to be repeated rumors coming out of FCC that maybe they should take a different approach to utilizing TV "white spaces" by licensing them for broadband. Perhaps some think this will solve the wireless microphone problem painlessly - it won't.


TV white spaces are the inevitable result of TV broadcast licensing, especially when there is uneven terrain and uneven population distribution. There will always be places where there is no usable TV signal on a channel and were lower power use of that channel by other services is possible without interference. Under analog TV there was a lot more such white space due to the "UHF taboos" necessary to avoid neighboring channel interference to TV sets with mediocre selectivity. (FCC efforts in the 1970s to improve TV selectivity and decrease white spaces went down in flames due to broadcaster opposition.)


Wireless mics can use TV white space to provide a useful service, but in doing so inevitably use spectrum inefficiently compared to other possible users of white space. Why? Wireless mic use is intermittent in both space and time and only uses a tiny fraction of the space/time/spectrum resource made available by TV white spaces. Hence use is heavy in the Broadway theatre district of Manhattan and in a few other theatre districts. Use is heavy near churches for a few hours a week. But reserving TV white spaces for the exclusive use of wireless mics denies the spectrum to other that can use it much more intensely.


The current wireless mic mess is a result of both benign neglect of FCC towards this sector and aggressive merchandising by mainly Shure, Inc. to large numbers of users ineligible under current FCC rules to use them. (The hypocrisy of the TV broadcasters for opposing Part 74 eligibility for the churches and theatres for years, if not decades, and then becoming Shure's "best buddy" during Docket 04-186 is certainly a case of "strange bedfellows".)


I have repeatedly written here that "wireless mics are a legitimate use of spectrum (that) deserves more from FCC than benign neglect that allows most users only criminal spectrum squatting" . Yet FCC has taken no action even on the relatively simple issue in Docket 08-166 of evicting wireless mics from the spectrum that is now licensed to others after the DTV transition, let alone the more complex issue in Docket 08-167 of whether action should be taken against anyone for flaunting the Commission's rules and creating a de facto reallocation of spectrum.


The only way to avoid the inefficient use of white space that would result from preserving the present squatting of large numbers of users is to move towards a new method of serving wireless mic needs that does not give them exclusive, hence inefficient, spectrum. Let me note that CMRS licensees already have the regulatory flexibility offer femtocell-like systems that transmit wireless mic signals on CMRS spectrum without interconnection to the public network - one way connections from the microphone to the theatre/church audio panel. While the microphones and analog-to-digital convertors (DAC) used in cell phones are not of sufficient sound quality for many wireless mic applications, there is enough CMRS bandwidth available now to permit adequate quality with better mics and DACs. If the CMRS crowd really wants 800 MHz below 3 GHz , maybe it should seriously think about helping FCC by proposing a practical alternative to the wireless mic impasse.


Another approach to solving wireless mic spectrum problems is to move this use to another band where it will have a compatible spectrum sharing partner. Since wireless mics are a distinctly short range service, such sharing should be possible. For starters, the 1435-1525 MHz aeronautical telemetry band might be considered.


But letting wireless mics just sit in white spaces will inevitably cause problems for both the current policy adopted under Docket 04-186 and any alternative path the Commission might go down.

TV White Space/TVBD R&O
Publication in Federal Register
(Expected) This Week

Remember the classic cartoon of the little boy sitting on the toilet with the caption that says "The job isn't finished until you complete the paperwork"? Well the same is true at FCC. The saga of Docket 04-186:

Event	Date
R&O Approval	11/4/08
Release of text	11/14/08
Release of Errata	1/4/09
FR Publication	2/18/09 ??

As a public service, I am giving a link to my interpretation of the Errata showing how it changed the original rules. Note there is no guarantee that the FR version of the new rules are the same as what I estimate they should be and the FR version is binding.

The publication will start a clock for the effective date of the new rules and will also open the door for appeals. It is expected that the broadcasters, perhaps together with their fellow travelers/odd companions at Shure, will not ask the FCC for reconsideration but will go directly to an obscure federal court thought to be supportive of vested interests. Others are expected to ask FCC directly for reconsideration of the details of the decision.

So don't expect TVBDs at your local Radio Shack in the next month or two.

UPDATE - Published 2/17/09
74 FR 7314,7332
(Citation is a link)

2nd UPDATE
Silicon Valley Mercury News reports that NAB & MSTV filed appeal on 2/27 in U.S. Court of Appeals for the D.C. Circuit.

Wireless Microphones and
Docket 04-186: Two Different Viewpoints

On May 1st, the Sports Technology Alliance, a trade group consisting of the major professional sports leagues and ESPN, submitted an ex parte filing to FCC on why the FCC should reject the TV whitespace proposals of Docket 04-186 because of the threat of harm to the production of live sports events or the possible resulting requirement that using beacons to protect legal wireless microphone use "would result in significant additional expense to acquire new equipment merely to enable existing equipment to continue to function." Presumably the "existing equipment" they mention is the analog FM FDMA equipment that is being replaced now in almost every other radio service by more efficient equipment.

To bolster their technical points, this group has hired Harbour Group, a Washington DC PR firm to explain the advantages of the status quo. Harbour's website explains their approach to advocacy:

“We have helped clients sharpen their messaging and delivery to provide support to their allies and put pressure on opponents, shaping the policy environment... Managing the public policy issues that can affect an organization’s success starts with identifying and prioritizing challenges. We conduct thoughtful research, target key constituencies, build successful alliances and mobilize supporters. Our collective backgrounds provide a powerful combination of expertise and experience that allow us to help shape policy development and deliver results.”

Oddly, Harbour has never mentioned why these multibillion dollar clients need continued cost free access to spectrum on demand anywhere in the US even if it denies the use of the spectrum to others and why they cling to using dated FM FDMA technology when even your neighborhood taxi is transitioning to more efficient technology.

SpectrumTalk welcomes Harbour Group to the fray and looks forward to the "pressure" they promise. However, the wireless microphone community might do better hiring technical advisers to see what their technical options really are rather than clinging to technical and regulatory approaches of the past.

Marcus Spectrum Solutions LLC has filed with FCC today a response to the Sports Technology Alliance. Readers are encouraged to compare the two viewpoints and comment on them. While I nominally "moderate" comments on this blog to prevent spam, all comments received will be posted below except those that are clearly spam or contain words not fit for broadcasting. I suppose Harbour Group would not suggest that the other side be as open.

A Wireless Microphone Manufacturer's Approach to Spectrum Management

In Docket 04-186 (TV Whitespace) the wireless microphone community has been making numerous complaints about how they can not be subject to any interference because they are such a vital service. Of course, the vast majority of present wireless microphone users are not eligible for licensed under Part 74, Subpart H so such use is actually a criminal violation of 47 USC 301. But setting that aside for the moment, let's see how responsible they have been. Below is a web page I downloaded for Shure's Wireless Frequency Finder website. I have made several annotations.

(Click on any of the images in this post to get a clearer version of the information shown)

First, next to the letter A is the following quote:

"As a rule, a wireless system should NOT operate on the same frequency as a local TVstation. The signal strength of a television transmission is many times stronger than that of a wireless system, and will result in interference."

I note that "rule" is not capitalized, so I assume that Shure is not referring to FCC Rules. You see the reason you should not pick an active local TV channel is that you might get interference. Shure apparently isn't concerned that TV viewers might get interference. Shure also isn't concerned about interference to weak distant TV stations, the problem that MSTV keeps complaining about for the proposed white space devices. Why is MSTV so worried about cognitive radio-based WSDs and oblivious to the present illegal use of UHF spectrum by "dumb" wireless mics?

Next, near the letter B, we have the following quote,

"Shure wireless microphones and PSM systems designed for use in the United States operate on standard VHF (TV channels 7-13, 174-216 MHz) and UHF, TV channels 14-69, 470-806 MHz, frequencies."

470-806 MHz? Does that sound familiar? Doesn't that include the frequencies that FCC
just auctioned off for $19B and AT&T and Verizon expect to start using in 306 days? Doesn't it include blocks that have been allocated to public safety? Did Shure forget to tell its customers? Perhaps they didn't read the newspapers about the auction? What are their customers really expecting? When is Shure going to urge them to move out of these 700 MHz channels? Note that the whole tone of the "spectrum finder" is that users should listen to Shure and just ignore FCC and everyone else.

Then I entered the FCC's ZIP code, 20554, in the Shure "frequency finder" and asked for frequencies in the DC area. Here are the results:

Well at least Shure does not recommend the frequencies that have been auctioned. But wait, isn't there something special about channels 17 & 18 in the Washington DC area? Weren't they allocated for TV Land Mobile Sharing in Docket 18262 in the 1970s?

Pulling out my brand new copy of 47 CFR I look up 90.303. Voila, in the Washington area 17 & 18 are land mobile public safety channels!

So I went to ULS and looked up the specific use of channels 17 and 18 in the DC area. Above is the list of 28 public safety agencies in the Washington area that use these frequencies. Did Shure ask them if it was OK for illegal nonlicensed users in a band subject to mandatory licensing to share their frequencies?

How could Shure have missed that? If Shure thinks sharing with public safety is so easy, why don't they file a petition and see what APCO thinks about it?

I have written previously that wireless microphones are a legitimate use of spectrum and that FCC should accommodate them in some way, but not necessarily with the same obsolescent technology forever and not necessarily in the same valuable spectrum that they use inefficiently (in terms of time and space availability) if they exclude all others. But the wireless microphone crowd should start acting responsibly first, not just urging their customers to squat on all sorts of frequencies including public safety frequencies.

Considering the lawless, reckless nature this group has shown, it is amazing that established trade groups like CTIA, NAB, and MSTV are all pandering to them. Normally these groups protect their own interests by stressing the need for compliance with FCC regulations, not explicitly condoning violations of them.

Google Flip-flops on White Space

Google filed a new letter at FCC on 3/21 changing its position on the Docket 04-186 TV white space proposal. After developing a listen-before-talk (LBT) detector, showing pictures of it, and leaving its antenna at the FCC Lab, they have decided to focus on the other two alternatives in the FCC's NPRM to avoid controversy. These alternatives were: geolocation (e.g. GPS) with database lookup and a local beacon to indicate what channels are available in a local area.

Google says,

"Under our own enhanced protection proposal, a TV white space device will not transmit on a channel until it first has received an "all clear" signal for that channel, either directly from a database of licensed transmitters in that area, or from a geo-located device with access to that database. That “permission to transmit” signal (at a maximum power level of 4W EIRP) would be sent on channels the geo-located device already knows are clear of licensed users. Any device without geo-location and database access would not transmit at all, unless and until it has successfully received advance permission from such a device."

If Google thinks this will make the controversy go away, I fear they are naive. While MSTV and NAB has focused on LBT as their main enemy, they have clearly dissed the other alternatives too: "The Notice’s Other Proposed Interference Prevention Techniques Would Be Ineffective" NAB and MSTV Reply Comments at p. 8

And even if the "immovable object" of the broadcasting community gives in to the "irresistible force" a little on the other two options, we then get into a question that has been lurking under the surface since the beginning of this rulemaking: where do you draw the line on the area where white space devices can operate?

MSTV has been cryptically talking about "protected contours" but has never defined that term or given a reference to any FCC rules that define it. In reality, FCC has defined the coverage area of TV stations in various ways for various purposes. Which definition would make MSTV happy? Remember MSTV has already said that there isn't any spectrum available for WSD use in major urban areas using their acceptable conditions. That says something about their thinking and is a hint of what will happen if Google and friends try to reach a negotiated understanding with MSTV.

NAB, however, has already blasted the Google letter/olive branch saying,

"We are pleased that Google now seems to realize that spectrum sensing alone won't protect viewers against interference from unlicensed devices. Unfortunately, simply adding geolocation and beacon sensing does not mean that mobile operation is suddenly feasible. Portable, mobile personal device operation in the same band as TV broadcasting continues to be a guaranteed recipe for producing interference and should not be allowed under any circumstances."

Google also hopes that they can make the wireless microphone problem go away also.

"Further, all TV white space devices would be blocked from transmitting by any wireless microphone beacon in that channel, using signals specifically designed to be easy to reliably detect, and coded to be identifiable to prevent abuse. These beacons should be quite inexpensive, and would be used in conjunction with existing wireless microphones, so there would be no need to replace legacy devices.

In addition, we are proposing a "safe harbor" for wireless microphones in channels 36-38. No TV white space device would be permitted to transmit in these channels. This will also protect medical telemetry devices and radio astronomy services, which are licensed to use channel 37."

Medical telemetry does indeed use "Channel 37" -- which is really a passive radio astronomy band. But this is an agreement FCC worked out, actually I was the one who proposed it, based on the fact that the medical telemetry equipment used is quite expensive, sold only to hospitals, and has a good history of compliance with licensed operation and rules. By contrast, the wireless microphone business is basically a "wild west" of spectrum squatters who are violating criminal laws in doing so and manufacturers who aid and abet this lawlessness. This is the group you want to share with medical telemetry and radio astronomy? Did anyone check if there is even enough capacity on channels 36-38 for broadway shows and live concerts with large numbers of microphones in major urban areas that may have TV stations on channels 35, 36, 38 and/or 39?

I suppose FCC would do anything to avoid making a decision here on spectrum policy and hopes that the Google position will be the basis of consensus. I suspect it will just introduce more controversy.

However, I hope that the ongoing FCC Lab tests will show that WSDs really do work with reasonable protection to the few (and ever decreasing) households that actually receive over-the-air television. As I wrote previously, the wireless mic problems should be addressed by more efficient wireless mic technology (not just ancient FM) and relocation to bands they can share with easier.

=============

Related post by Sascha Meinrath

Wireless Mics are a Legitimate Use of Spectrum:
They Deserve More from FCC than
Benign Neglect that Allows Most Users
Only Criminal Spectrum Squatting

My former FCC boss, Dale Hatfield, used to say "if you are looking for interesting new ideas in spectrum policy, look what people are doing illegally and legalize it."

Well most wireless microphone use at present is illegal, a point that many people like to ignore - like the elephant in the room. Why are they illegal? Most wireless microphones in the US are physically Part 74 (broadcast auxiliary) devices operating in UHF TV spectrum in "white space channels" and require licenses. Only those industries specifically enumerated in Part 74 are eligible for such licenses and these are basically only NAB members and Hollywood moguls - all of whom have effective lobbyists in Washington. It is a cozy arrangement born in a different era of both technology and spectrum policy but it is a bad anachronism.

How did we get there?

In ancient history there was only analog television in UHF spectrum. The "UHF taboos" that resulted from both NTSC technology and 1953 estimates of how well future production TV sets could reject signals on nearby channels became self fulfilling prophecies and resulted in only 1 out of 6 channels being used in a given city. There was always tons of white space under this regulatory scheme. The "club" of broadcasters in a given city knew each other well and could work out deals to use this white space in support of their operations without interference. They sought and received FCC blessing for this exclusive use, although at some point Hollywood weighed in and became eligible also. Live theater productions, live concerts, churches, and conference centers are not eligible under Part 74 so their only legal options are low powered unlicensed systems that are secondary (and hence have greater risks of receiving interference) or Part 90 systems with complicated licensing requirements that probably have license transaction costs that exceed hardware costs in many cases.

Some unethical manufacturers and their dealers took advantage of this scenario and started marketing Part 74 wireless mics to noneligibles and "fuzzified" the legal issues. One even has on its website a "Wireless Frequency Finder" to help its customers find frequencies to use illegally. Apparently the FCC has turned a blind eye to this situation for years.

Lord Nelson raising his telescope to his blind eye in the Battle of Copenhagen

That was then, this is now

All of this was tolerable when spectrum was not in great demand, the dominant spectrum policy model was "command and control", there were few technical options for other use of the this spectrum, and there was plenty of white space. But that is all obsolete or becoming obsolete. Even as I write this the 700 MHz auction is winding down and next year TV channels 52-69 will be in the hands of new licensees who will expect to use them after a multibillion dollar auction. The NPRM in Docket 04-186 proposed 3 different options to use white space for broadband distribution in both urban and rural areas. While the broadcasters question the listen-before-talk option and have dragged everyone into obscure testing issues as a delaying tactic, the other 2 options are still on the table without significant objections.

The same wireless mic manufacturers who created the present lawless situation want the FCC to kill off the 04-186 proposals and allowed endless illegal squatting of their customers. The basic problem is that this would result in negligible overall use of a valuable resource: In the best circumstances the spectrum would be used heavily in the Broadway theater district, near megachurches on Sundays, and on the Las Vegas Strip. In terms of space and time, overall spectrum use would be negligible and it would be denied to all other classes of users.

The new technology proposed in 04-186 would result in much greater spectrum user and benefit to both the economy and society, but this should not mean that wireless mic users should be "thrown to the dogs". The users of wireless mics perform valuable are entitled to spectrum access, but access consistent with the current concepts of spectrum policy. They seem to demand continued exclusive access to "free spectrum" - even for clearly commercial operations. Guys, that is not the current era of spectrum policy.

Options for the future

But FCC should find a way to legitimize spectrum access for these users. Keeping them in the UHF-TV band will deny this spectrum to more valuable users but just as FCC relocated hospital-based medical telemetry out of this band into other bands where sharing was feasible, it should enter into a dialog with the wireless mic community (amnesty?) to find new spectrum home(s) where wireless mic use can share with other users on an interference free basis. Maybe there is a need for a coordinator who will charge fees like in the UK. (JFMG is the Ofcom-designated coordinator what what is called "PMSE" in UK-speak.) Unlicensed use and Part 90 use remains an option for users with modest requirements. Audio-Technica, a major supplier, has invested in and developed high reliability ultrawideband-based systems that can

Audio-Technica UWB-based wireless microphone system using MSSI's technology

satisfy the needs of users with needs for less than 14 units in a theater and can live with 12 kHz upper audio range - adequate for many users, but not opera. (This appears not to be a basic technical limit, but rather problems of an initial design of a niche product that uses off the shelf components.) A previous post here described how a AWS (3G) spectrum-based service could serve upper end users with high density and high audio quality requirements. Yes, it would result in increased costs for spectrum access. But that is the past 20 years of spectrum policy in the US and many other countries.

Finally, one problem the US wireless microphone manufacturers face is that they are relatively small firms with niche markets and do not have a good R&D base or volumes that easily justify custom integrated circuits. Thus they tend to stay with the existing technology and not press the margins to get new products. Thus they also are spending money on lawyers to press the FCC rather than innovating - like the medical telemetry people did when they noticed the same problem with the TV band. Ausio-Technica, as mentioned above, stands out as a recent innovator because they contracted with Multispectral Solutions (MSSI) of Germantown, MD for their new UWB product. They didn't spend all their money on lawyers!

Conservative wireless mic companies watch out! The problem isn't just Docket 04-186, Sony is entering your field too with new technology. Surf over to www.sonybiz.net/go-digital and you will see that Sony believes that digital will work for wireless mics and has entered the UK market. Fortunately for the not so nimble US manufacturers the present Sony models only work in 798-862 MHz and can't be used (legally) in the US market except in a small segment that will disappear in 11 months. But it wouldn't take much to move these to another band other than UHF-TV. Marrying the Sony analog-to-digital conversion technology to 3G/AWS cell phone technology should also be straightforward.

But the key issue is that FCC is not now considering any other options for wireless mics at the moment. The status quo is an inefficient anachronistic use of valuable spectrum and will have real problems next year when the 700 MHz auction winners claim their spectrum.

Possible options that should be examined should include the possibility of opening a new band, other than UHF TV. that is more compatible with sharing with the wireless mic industry as it actually exists today along with use of more efficient technology than the current de facto monoculture of FM. The demands of the wireless mic users that the new spectrum access should have no cost should be considered but should not be treated as a "non-negotiable demand". UK wireless mic users pay for access so there is a relevant precedent. The longer FCC ignores this issue, the more difficult it will become.

================================
Harold Feld has published an interesting follow up to this post entitled "700 MHz Aftermath: Verizon, AT&T & the $16 Billion Termites"

TV White Space Device Testing Off and Running

Yesterday at 10 AM a crowd of about 30 gathered at the FCC Lab in Columbia Maryland to watch the beginning of Phase 2 of the Docket 04-186 White Space Device testing. Four devices are being testing: Adaptrum, Microsoft, Motorola, and Philips. Some are detectors only, some are both detectors and transmitters.

It was announced that a fifth unit from Singapore Institute for Infocomm Research (I²R - pronounced "i-squared-r") was on the way from Singapore for testing but had a shipping hangup with DHL that had trouble posting a bond for reexport with US Customs and shipped the unit back to Singapore. I²R is now using a different shipper and arrival is expected shortly.

The Google prototype is missing in action without any explanation and FCC staff was vague about whether additional units would be accepted - implying that this was subject to the Chairman's usual micromanagement.

It was announced that testing schedule updates would be posted on the testing web site.
[But no information has actually been posted to date. I was amused to hear that in the current FCC micromanagement environment, the Chairman's Office approval was needed for OET to post information to this site and had been obtained.]

As I speculated in the previous post, different developers got different guidance from the FCC staff on what interfaces from the devices were requested to speed testing. Philips was told to indicate the results of 30 trials to detect a given frequency and interpreted to give a percentage of the tries that indicated the frequency was in use. Adaptrum was asked more specifically to deliver a text string of zeroes and ones indicating the outcome of each trial. I suspect this inconsistency comes from the inability of FCC staff members to issue written guidance on even such microscopic matters without multiple layers of oversight - so they just issue inconsistent verbal guidance.



When the testing started the 30 observers gathers in a lab room and watch initial testing of the Philips units with undistorted DTV signals from a Rhode and Schwarz signal generator fed directly into their device. Testing started at -110 dBm and reach -120 dBm when we broke for lunch. At that point the Philips device still had a perfect detection record.



MSTV observers repeated questioned whether devices might just always declare a signal was present to get a perfect record. Apparently MSTV has no faith in market forces since such a device would fail in the market as it would never transmit a signal and also never cause interference. MSTV also quibbled whether smaller antennas might make detectors less sensitive. While this is true in a technical sense, it is irrelevant for policy consideration since the FCC proposal, the position of most parties, and the 5 GHz U-NII precedent deals with system performance not just the detector electronics: if the total system doesn't meet the performance standard in the final rule, if can't be sold.



The initial testing also revealed the ambiguities in the published test plan. The first test, I.A, was testing detection at various DTV signal levels. The procedure actually used was to use a Rhode & Schwarz SFU signal generator to directly produce signals at levels in the -110 dBm range (much more sensitive than DTV receivers) and below and to send them by cable to the equipment under test (EUT) a few feet away. There are lingering doubts whether the signal reaching the nearby EUT in such a setup are actually the power indicated on the SFU since at such very low signal levels unintended paths might create comparable signals. Oddly, a nearby screen room was not used for this test and would have decreased uncertainty about unintended coupling. The test plan did not address this level of detail.



Indeed, it is puzzling why all this testing is necessary: In the 5 GHz case, NTIA and FCC determined 2 pairs of detection levels and maximum transmit power that would protect the cochannel radar systems and left it to industry to develop systems that met the standard. Truly a pass/fail system. The existence of such a rule would stimulate capital formation to finance the development of such systems while reliably protecting the few homes that receiver over-the-air TV reception. The current lingering uncertainty about what the standard is and the confusion of that issue with prototype testing is a big disincentive to capital formation - something I would have thought a Republican administration would understand.



At the birth of Wi-Fi and Bluetooth in Docket 81-413 many parties of vested interests quibbled over whether affordable electronic could be built to meet the rules. Wisely the Commission chose a fail/safe approach of adopting a standard that protected other systems and just waited to see if anyone could build equipment. Within 2 years the first commercial product reached the market from a startup firm and several years later 802.11 standardization began. Now that Wi-Fi and Bluetooth are household names, few remember the uncertainties of the 1980s.

White Space Device Testing
to Start at FCC Lab

A January 17th FCC public notice announced the beginning of the next round of testing of prototype white space devices (WSDs) on January 24 at 10 AM and will continue "4 to 6 weeks". the testing will be "conducted openly and transparently" although few details were given about procedures in the published test plan.

The notice indicated that devices from Adaptrum, Microsoft, Motorola and Philips would be tested but was ambiguous about whether late entries would be allowed. Google is thought to have a device also so we will see if they show up and will be allowed to participate with others.

Other unanswered questions about the testing include: What is the last date, if any, that developers can change the software in their prototypes? When can the developers show FCC staff how to operate the devices? FCC staff has informally told developers what type of data they want from the devices during test, e.g. a comma separated variable (CSV) list of yes/no detections for 30 consecutive trials at a given power level. Have all developers been told the same set of requirements?

So the restaurant business near the FCC Lab should pick up for the next few weeks. Hope they plow the parking lot for the expected guests. See you there!

UK's Ofcom Proposes Unlicensed TV White Space Devices


Yesterday, the FCC's UK progressive counterpart, released a long awaited report entitled "Digital Dividend Review:A statement on our approach to awarding the digital dividend". "Digital dividend" is Eurospeak for what happens to TV spectrum after the end of the DTV transition, analogous to the FCC's 700 MHz auctions.

Ofcom stated (in peculiar UK spelling) the following points that I strongly agree with:

This decision matters for several reasons:

• spectrum is an essential input in the modern world. Its use underpins 3% of the UK’s gross domestic product (GDP) and generates wide reaching benefits for citizens and consumers. But spectrum is a scarce resource, so how it is managed is a critical issue;
• the spectrum presently used by analogue terrestrial television is exceptional because it can readily be used to provide high bandwidth services over long distances and into buildings; and
• the opportunity to put this spectrum to new use does not arise often. Analogue television has been its main use for many decades, under a framework that dates back to 1961.

... Under the Communications Act 2003, our duties are to further the interests of citizens and consumers and to secure the optimal use of spectrum. Our objective for the DDR is to award the digital dividend in a way that maximises the total value to society from its future use. This includes value both to citizens and to consumers.

• 
  

These would be admirable goals in any country. Then comes the real shocker, the UK counterpart of the FCC's Docket 04-186 proposals for white space/"interleaved spectrum" in UK-speak:

1.34 We propose to allow licence exempt use of interleaved spectrum for cognitive devices. Some licence exempt uses are able to coexist successfully with higher power licensed uses. Cognitive radio is a new technology that can detect spectrum that is otherwise unused and transmit without causing harmful interference. It has the potential to support a wide range of uses, including high speed always on broadband. It is particularly suited to operating in interleaved spectrum, where significant capacity is often unused at any one location at least some of the time.

1.35 We see significant scope for cognitive equipment using interleaved spectrum to emerge and to benefit from international economies of scale. But use of equipment in the UK will need to protect licensed users of this spectrum, including DTT and PMSE, against harmful interference. We will not allow cognitive equipment to use interleaved spectrum until we are satisfied on this point.

1.36 We think that allowing licence exempt cognitive use of interleaved spectrum is likely to be justified. Allowing access in this way will overcome the coordination problem they would otherwise face while imposing limited costs on other potential uses. We also think it is likely to encourage more innovation and competition in the provision of services, promoting the interests of citizens and consumers.

... 6.26 In contrast, cognitive devices could make flexible use of interleaved spectrum without causing harmful interference to licensed users. This would allow many of the applications set out above to be delivered at a low opportunity cost, resulting in substantial benefits. Other applications and innovations might also be spurred by the availability of a large pool of interleaved spectrum for licence exempt use.

6.27 Cognitive use of interleaved spectrum would depend on the development of effective spectrum sensing technology that would avoid transmitting in channels used by licensed services. Devices are being developed by a number of manufacturers, including Microsoft, Motorola and Philips. These companies have each submitted devices to the FCC for testing in the US. These devices are primarily designed to detect DTT and wireless microphone signals and, as such, would be suited for use in interleaved spectrum in the UK.

6.28 We therefore propose to allow cognitive technologies to use interleaved spectrum on a licence exempt basis subject to establishing that the probability of harmful interference to licensed users will be low. It is likely that the total value generated would be greater than the opportunity cost of allowing licence exempt cognitive access. The total value would be composed of the private value of foreseen
applications, which we estimate to be approximately £150-250m (NPV over 20 years), as well as benefits that would come from innovation and new services. There may also be broader social benefits. Because cognitive devices do not need to be exclusively assigned rights to spectrum and should automatically avoid interfering with licensed services, the opportunity cost should be low.

6.29 We would need to specify a number of parameters to which equipment would need to adhere. Early measurements made by the FCC suggest that such spectrum sensing is possible but careful certification might be needed.* It may take some years to undertake the work necessary to gain appropriate international harmonisation. (Emphasis added)

* Looks like Ofcom reads the FCC documents differently than MSTV and NAB! - MJM

In UK-speak, wireless microphones are called "programme making and special events"/PMSE and handled on a strictly licensed basis, apparently without the wholesale violations as in the US, by a private coordinator, JFMG, Ltd., who charges fees to all PMSE users based on the amount of usage. Unlike the FCC, Ofcom is making explicit plans for PMSE after the digital transition and they will have to pay for spectrum use, as is the general trend for spectrum access in both US and UK. Oddly, in the US both the legal and (majority) illegal wireless microphones users assume they have a constitutional right to free spectrum use with existing equipment in perpetuity, unlike most spectrum users.

On the PMSE issue, Ofcom states

1.41 We have decided to reserve most of the available interleaved spectrum to meet the needs of PMSE users. PMSE is an existing use of interleaved spectrum. It comprises a large and diverse community of businesses, community organisations and individuals. We think that PMSE users would find it difficult to coordinate a bid for access to spectrum, and we think there is a high risk of market failure as result. However, with a careful transition, they can move to accessing spectrum via market mechanisms in the future.

1.42 We will award a single package of interleaved spectrum to a licensee that will act as a band manager. To help PMSE users with the transition to market mechanisms, we will use criteria designed to ensure that the band manager’s interests are aligned with those of PMSE users. The band manager will pay a charge for the spectrum based on Administered Incentive Pricing (AIP) and will be able to earn revenue by charging its customers for access. But regulation will ensure that it has to meet reasonable demand from PMSE users on fair, reasonable and non-discriminatory terms. So long as these obligations are met, the band manager will be able to allow others to make use of its spectrum.

1.43 We have decided that channel 69 should continue to be available for PMSE use throughout the UK on a licensed basis. We will also promote greater licence exempt use of channel 70 for PMSE, in the interests of community users.

So one TV channel (#69 in the UK channel plan whihc is not the same as the US plan) will be available for wireless microphones through the coordinator independent of any auction. Some of the remaining white space will available to wireless microphones through the coordination.

In another UK development that will be bound to displease the US broadcast establishment, Ofcom has published proposals to squeeze multiple HDTV transmissions into a single DTV transmitter. Remember when we thought TV broadcasters should get one new 6 MHz channel for their old NTSC channel because 6 MHz was needed for HDTV? Ofcom stated,

1.14 We have identified two technical advances that together could result in a very significant increase in the DTT (=digital terrestrial television in Eurospeak) platform’s capacity. These relate to improvements in the standards used (a) for coding (compressing) information, to squeeze as much as possible into a given amount of spectrum, and (b) in its physical transmission.

1.15 The two changes are:

• An improved video and audio coding compression standard called MPEG-4 . This is expected (over time) to operate at up to double the efficiency of the coding standard that is used at the moment on DTT, MPEG-2. This means that a DTT multiplex* could carry up to twice as many services using MPEG-4 as can currently be achieved using MPEG-2, whilst maintaining similar picture quality.
• A new transmission standard, known as DVB-T2. This is expected to deliver an increase of at least 30% in the capacity of a DTT multiplex over the current standard, whilst maintaining the same coverage. This standard is a development of the existing DVB-T standard used in the UK since 1998. DVB-T2 is still undergoing development by DVB in Geneva, but is expected to be finalised in spring 2008.

1.16 It is important to note that MPEG-4 and DVB-T2 differ in one important respect. MPEG-4 can be introduced within a multiplex (so it can offer a mix of services coded in MPEG-2 and MPEG-4). But the introduction of DVB-T2 requires a whole multiplex to be converted from DVB-T. This is, of course, a larger step-change.

1.17 The introduction of these two technologies could, if combined, increase the capacity of a multiplex by up to 160%. This is a very large increase. It is the equivalent of raising the number of Standard Definition (SD) services that can be carried on a DTT multiplex from around eight currently to around 13-15 at DSO, and over 20 in the longer term. HD is generally regarded as unfeasible on DTT in the UK without use of MPEG-4: but with the use of these two technologies combined, a single DTT multiplex could in time offer at least four HD services.

* DTT = digital terrestrial transmission. In UK and many European countries, broadcasters do not own and operate their own transmitter, rather DTV signals are transmitted on multiplexed transmitters owned by a middle man with several signals on each transmitter and channel. Under present UK policy no HDTV is transmitted over the air because it was thought that multiplexing HDTV signals was impossible. Now Ofcom thinks it is possible. - MJM

Now UK channels are different than US channels so all the details don't apply here. But the nagging question is whether the US erred in giving established broadcasters 6 MHz for HDTV and whether we could get our own "digital dividend" by making TV broadcasters double up on multiplex transmitters. I suppose the suggestion will not get me an invitation to the next NAB convention.

Google white space device prototype

Busy Week of White Space Action

It's been a busy week here in Washington, my home town. Down at the lab of our local communications commission there have been all sorts of visitors, like Magi at Xmas time, bearing gifts or promises of gifts. Fortunately, unlike the advocates of the status quo for large affluent TV broadcasters who skirt the Commission's ex parte rules with apparent impunity, these visitors believe in and act in the letter and spirit of transparency. Thus there is a paper trail where we can follow the action.

Actually, a little earlier on November 16 Motorola came by with the first recent present. Motorola described it as follows

"(It) uses geo-location database that is augmented by sensing algorithms to determine which TV White Space channels are available for use. The device also can be configured to perform testing of the DTV sensing algorithms but is not a normal operational mode of the device."

No pictures were included, but I saw the device at the Lab and it is rack mounted in an 18" high rack.

On December 4, Google dropped by.

(The) Google representatives demonstrated broadband spectrum sensing technologies that reliably detect DTV signals well below the noise floor. The broadband DTV sync signals gave reliable power level estimates, even when the pilot is deeply faded, removing the need for large margins. preliminary figures from the initial phase of the testing support an average sensitivity of -120 dBm.

The picture at the top of this post was included in their submission to FCC.

Then on December 5, Adaptrum, Inc , a client of mine, dropped by with its unit.

Dr. Haiyun Tang of Adaptrum and Steve Jones of FCC Laboratory with Adaptrum White Space Device (WSD) at delivery to FCC for testing,

Adaptrum said in its filing

The Adaptrum device is different from others that have been discussed on the public record in that it is not based frequency domain processing and threshold detection of DTV pilot tone power. Rather, it uses the whole 6 MHz of the DTV signal and contains a time domain matched filter. This greatly increased bandwidth permits greater sensitivity than pilot tone detectors.

Note that the Google and Adaptrum filings were made almost simultaneously and that both systems appear to use the same type of time domain processing.

Also on December 5, my former boss, Ed Thomas, met FCC downtown on behalf of both Microsoft and Philips. The filing says

During this meeting, Mr. Thomas made arrangements for Microsoft and Philips to submit devices to OET for the next round of white space prototype testing, and the parties discussed white space testing logistics, including potential dates for laboratory and field tests.

Are Microsoft and Philips now combining forces and working on a common device? The letter is ambiguous so we will see.

FCC staff reports that the "8th Floor" has now said that all submitted devices will be tested in parallel and publicly with observers from the interested public - please don't throw peanuts at the FCC staff. This apparently includes both bench tests and field tests. A problem appears to be how to find homes to test these in where an unlimited number of observers can wander in and out. Stay tuned.