SpectrumTalk

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.