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Ofcom bullish on Dynamic Spectrum Access

From "Dynamic spectrum access could revolutionise comms," by David Meyer, ZDNet UK, 14 November:

"Ofcom has published its second annual report looking into future technologies that may enable a more efficient use of radio spectrum.

"An emerging technology called dynamic spectrum access (DSA) is one option that the telecommunications regulator thinks might be very useful, according to the Technology Research and Development Report, published on Tuesday.

"Ofcom suggests that emerging technologies explored through its Treasury-funded R&D programme could generate up to £6.5bn for the UK economy over the next 20 years...

"DSA would effectively decentralise spectrum control by letting a communication device, such as a mobile phone, roam between different wireless networks - and that means different operators' networks as well as different types of network.

"According to Ofcom, this would 'make efficient use of the spectrum by linking the supply of spectrum with demand though an open and competitive marketplace for real time access to spectrum', as opposed to having chunks of spectrum allocated to specific services...

"Although roaming between Wi-Fi and cellular connectivity is already central to the fixed-mobile convergence being introduced by the likes of BT and Orange - another thing that Ofcom is very keen on - DSA would hinge on a 'system to allow network operators to transmit pricing information to handsets', leaving the handsets to then 'intelligently roam' across different networks.

"Asked why an operator would choose to allow its subscribers to roam across to a rival network or access point, thus depriving it of revenue, the spokesperson suggested that... 'Operators could feel they have a competitive advantage by doing this'.

"Analyst Dean Bubley said the idea of dynamic spectrum access was 'great from a scientific and theoretical point of view', but asked: 'If it was a UK-only initiative, would there be enough volume in creating devices and device software for it?'

"The report also suggested that mesh networking might aid in the fight for spectrum efficiency. This involves low-cost, self-organising networks of access points, automatically connecting with other nodes that are within range and re-routing traffic if a node fails. Ofcom believes mesh networks could help extend broadband access and might find an application in the transport and healthcare sectors...

" 'We think it's a useful technology but we haven't formed any policies on it,' said Ofcom's spokesperson.
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NOTE: Section 5.5 of Ofcom's Technology R&D Report looks at "Licence exempt use of the spectrum." Here are some excerpts:

"As we said in our Spectrum Framework Review, a key decision for Ofcom is the balance between this and other spectrum management approaches. In considering the amount of spectrum a number of questions and issues must be considered, including:

1. "How should we choose whether bands of the radio spectrum should be made licence exempt, or whether another approach should be adopted?
2. "Should a specific type or class of devices be allowed in a band, or should the band be for many types of devices?
3. "Should licence exemption be the approach used for the higher frequency bands where spectrum is relatively underutilised?
4. "Should politeness protocols be mandated for efficient use of the bands?
5. "Would a licence exemption approach be helpful in allowing emergence of last mile wireless communications?"
6. "What are the levels of usage of the existing licence exempt bands? Is there any evidence of congestion? Our work here is discussed further in Section 3 regarding spectrum monitoring.

"To address a number of such questions in a comprehensive manner, Ofcom is undertaking a strategic review of its approach to Licence Exempt spectrum. We plan to consult on our findings in this area early next year. [emphasis added] We have research projects underway tackling each of the above questions and we describe examples of our early findings for two projects below.

"Should politeness protocols be mandated in the future for licence exempt bands?

"A politeness protocol specifies some rules and methods used for wireless communications in a license exempt band, often termed an enhanced commons approach. By mandating such an approach it may be possible to improve upon the device's robustness to interference or its ability to share with others. The resultant improved spectral efficiency and possibly higher power transmissions could allow for increasing growth in usage without excessive interference.

"The research conducted in this area has broadly concluded that overall Polite Protocols do provide a technical and net economic benefit. The research considered two scenarios, a Public Space WiFi Scenario and a residential WiFi scenario, and estimated a net economic benefit to the UK economy of £280M and of £500M over the first five years through introduction of Politeness Protocols.

"The main benefits of Polite Protocols arise from their use in areas of high congestion, and it is in these situations that mandating their use should be considered - if congestion is not predicted to arise, then Polite Protocols... reduce [spectral] efficiency due to the overhead of the protocol. Because of this, the research has concluded that mandating of Politeness Protocols should be considered on an application specific basis...

"Politeness protocols could also result in less coordination being required across operators and provide users with protection against catastrophic interference. Such certainty could promote technical innovation and the introduction of new services. It might be the case that adoption of Polite Protocols will be market led...

"Would wireless last mile communications benefit from a licence exempt approach?

"In response to the Spectrum Framework Review consultation, some suggested that the Digital Dividend released by the Digital Switchover process would be suitable for last mile applications under a licence exempt regime, possibly using mesh technology. We have thus commissioned research to assess the use of wireless technologies to achieve competitive and ubiquitous access to last mile broadband communications whether in a licensed or licence exempt approach.

"The research has concluded that wireless will be unlikely to have a majority part to play in the Last Mile for the next 20 years, although it may feature in offering lower Last Mile rates to a minority of users.

"Spectrum below 1GHz such as that available from the Digital Dividend, has the potential to offer an economic case for wireless broadband provision because the favourable propagation conditions allow large operating ranges. This could be of advantage in areas where ADSL cannot offer broadband access, for example rural areas, and also to reduce the number of base stations required. However there is limited spectrum availability in the DDR band, and it is concluded that while the bandwidth available could meet today's consumer requirements, in the future this is less likely, and so the ongoing business case for private ventures may become relatively weak. To meet future requirements such as HD-TV and Web 2.0 applications, the lack of bandwidth available below 1GHz is a barrier.

"The research study has concluded that a wired approach remains the likely major technology for last mile provision. The economic case for a fibre-optic wired last mile is now stronger... Hence, the provision of ubiquitous broadband is unlikely to be achieved through solely a wireless approach. Ubiquitous access could be better achieved by a joined-up broadband approach, allowing the peering of all forms of access, wired or wireless, to increase availability and bandwidth together...

[Spectrum Policy 16 November 2006]