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.

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.

700 MHz Auction About to Start - But FCC Hasn't Evicted Wireless Microphones Yet

In Docket 04-186, the "TV Whitespace" rulemaking, there has been a lot of discussion about wireless microphones. These are devices supposedly used only by TV broadcasters and other broadcast industry eligibles defined in 74.832. Of course, most users are other audio-visual operators whose use is illegal. Indeed, today I spoke at IEEE Globecom and used a Shure wireless microphone operating at 525 MHz. This is a misdemeanor violation of 47 USC 301. I feel guilty so I am confessing to my blog readers. (Perhaps this confession will make FCC come after me!)

January 24, 2008 the 700 MHz auction starts. But a review today of the current text of 47 CFR 74.802 shows , guess what, wireless microphones are still there and have no stated eviction date!

Here's the current text:

§ 74.802 Frequency assignment.

(a) Frequencies within the following bands may be assigned for use by low power auxiliary stations:

26.100–26.480 MHz

54.000–72.000 MHz

76.000–88.000 MHz

161.625–161.775 MHz (except in Puerto Rico or the Virgin Islands)

174.000–216.000 MHz

450.000–451.000 MHz

455.000–456.000 MHz

470.000–488.000 MHz

488.000–494.000 MHz (except Hawaii)

494.000–608.000 MHz

614.000–806.000 MHz

944.000–952.000 MHz

(Emphasis added)

Then the current text of 47 CFR 74.803 deals with who they can't interfere with:

§ 74.803 Frequency selection to avoid interference.

(a) Where two or more low power auxiliary licensees need to operate in the same area, the licensees shall endeavor to select frequencies or schedule operation in such manner as to avoid mutual interference. If a mutually satisfactory arrangement cannot be reached, the Commission shall be notified and it will specify the frequency or frequencies to be employed by each licensee.

(b) The selection of frequencies in the bands allocated for TV broadcasting for use in any area shall be guided by the need to avoid interference to TV broadcast reception. In these bands, low power auxiliary station usage is secondary to TV broadcasting and land mobile stations operating in the UHF-TV spectrum and must not cause harmful interference. If such interference occurs, low power auxiliary station operation must immediately cease and may not be resumed until the interference problem has been resolved.

See any requirement not to interfere with 700 MHz CMRS licensees? So before you bid a few billion dollars, you might want to ask FCC to clarify what is going on here.

700 MHz Public Safety/Private Partnership - FCC Votes to Implement Marcus "Interruptible Spectrum" Proposal


Yesterday's Commission meeting got lots of press coverage in the national media. Almost all of it focusing on Google's request open access to part of the 700 MHz band. This post deals with another issue that got less press coverage.

Here are some key quotes from the FCC Press Release:

Today's Order establishes a framework for a 700 MHz Public Safety/Private Partnership between the licensee for one of the commercial spectrum blocks and the licensee for the public safety broadband spectrum. As part of the Partnership, the commercial licensee will build out a nationwide, interoperable broadband network for the use of public safety. This network will facilitate effective communications among first responders not just in emergencies, but as part of cooperative communications plans that will enable first responders from different disciplines, such as police and fire departments, and jurisdictions to work together in emergency preparedness and response. Under the Partnership, the Public Safety Broadband Licensee will have priority access to the commercial spectrum in times of emergency, and the commercial licensee will have preemptible, secondary access to the public safety broadband spectrum. Many national and local public safety organizations have expressed support for a public safety/private partnership approach. Providing for shared infrastructure will help achieve significant cost efficiencies while maximizing public safety's access to interoperable broadband spectrum.

Public Safety/Private Partnership

• The Upper D Block commercial licensee and the Public Safety Broadband Licensee will form a Public Safety/Private Partnership to develop a shared, nationwide interoperable network for both commercial and public safety users.

The terms of the Partnership will be governed both by FCC rules and by the details of the Network Sharing Agreement (NSA) to be negotiated by the Upper D Block commercial licensee and the Public Safety Broadband Licensee. The NSA is subject to FCC approval, and must contain certain provisions such as service fees and a detailed build-out schedule for the network.

Chairman Martin issued the following on this issue,

While I also would have supported a network exclusively for the use of public
safety, the simple reality is that there currently is no way to fund such an enterprise. The use of a public safety-private partnership, however, creates an opportunity to provide state-of-the-art technologies to our Nation’s first responders in a timely and affordable manner. Many national and local public safety organizations have expressed support for a public-private partnership approach as their last, best chance to make this network a reality. We cannot afford to let the opportunity that the 700 MHz band offers for public safety pass us by.

The adoption of a National Public Safety Broadband Licensee to be a part of this partnership is also the best way to establish a truly interoperable network. The local licensing regime that has been used to date has resulted in a patchwork of networks that do not talk to each other. We cannot keep licensing public safety spectrum in the same manner as before and expect a different result. A National Public Safety Broadband Licensee will facilitate a unified national approach to the use of this spectrum, finally enabling all public safety users to talk to each other during a crisis. I therefore wholly support the public safety-private partnership adopted in today’s order.

The diagram at the top of this post comes from a 2003 internal FCC paper I wrote as part of the Spectrum Policy Task Force (SPTF) deliberations. (I have now posted this paper on my website.) The diagram below comes from the FCC band plan that has been released. There are certain similarities and it is pleasing to see that the concept has been adopted.




In view of the implicit and unannounced abolition of the SPTF, the Commission probably doesn't want to be reminded that this was actually SPTF Recommendation #27:

27. Address additional public safety needs through alternative “safety valve” mechanisms
to make spectrum is available to public safety in emergency situations when more
capacity is needed.

a. Because some public safety spectrum use is characterized by intermittent
“spikes,” public safety users should have flexibility to lease spectrum capacity
that is available during lower-use periods to commercial users with a “take-back”
mechanism when public safety use increases.

b. For major regional or national emergencies, additional public safety spectrum
needs should be addressed through enhanced easement rights to non-public safety
spectrum.

The SPTF paper referenced above dealt with both non-Federal Government public safety spectrum, e.g. state and local police and fire users, and Federal Government spectrum regulated by NTIA pursuant to 47 USC 305 that has the same high peak, low average utilization as state and local public safety. NTIA staff has a "temper tantrum" on this issue and threatened to have the head of NTIA complain to the FCC Chairman if the SPTF report even mentioned the possibility that NTIA-regulated spectrum might be shared in such a mode with civil users. Hopefully, now that FCC has taken this bold action, NTIA will at least tolerate public discussion of the topic with respect to the spectrum they control. Chairman Martin's above insightful comments really apply to all spectrum used for public safety purposes.

My paper for the 2005 IEEE DySPAN conference also explores the same issue and has been publicly available for a while. I would be glad to help parties preparing for the 700 MHz auction understand the options and opportunities that result from the FCC's bold action yesterday.