Ofcom consults on whitespace co-existance

Ofcom, the Super regulator that handles radio spectrum as part of its remit, is holding a consultation on the coexistence of whitespace devices.

Whitespace is the spectrum that is unused in certain areas due to geographic transmission systems that can not overlap and in this case relates to the UHF TV channels (470 MHz to 790 MHz). As there are multiple transmitters across the UK, adjacent transmitters can not operate in the same frequency bands (especially for digital TV) or the transmitters would interfere with each other.

This leads to large chunks of the UHF spectrum not being used in a particular geographic zone, which could be used for other purposes (as long as it was low power and didn't reach neighbouring areas).

Current plans are that whitespace devices will monitor what bands are in use (by listening to those frequencies) and thus not use them, in the UK they must also contact a central database, report their location and the database will specify what frequencies are available and what power they can transmit at.

There are other services that can also be interfered with such as program making and special events (PMSE) - things like outside broadcast units which can use some of the spectrum for remote TV cameras and such like, which also have to be catered for.

Ofcom have already said they will allow whitespace use on a license exempt basis, but they also must ensure that there will be no harmful interference to digital terrestrial television (DTT) and PMSE.

Whitespace technology is new and thus there is some uncertainty on how whitespace devices may interfere with DTT or PMSE services. However Ofcom doesn't want to overly constrain whitespace use such that large amounts of spectrum go unused, or that power levels/etc are so restrictive that reaching any sizeable population is unrealistic.

Ofcom will currently err on the side of caution and setting parameters that can be relaxed in future. Later this year there will be a set of pilot trials across the UK with a number of service providers where the increased power levels can be used for limited periods of time to ensure interference doesn't occur. The trials (and stakeholder consultations) will continue until Summer 2014 and will help Ofcom set the parameters for future national whitespace roll-outs starting in Q3 2014.

Ofcom has set the parameters and algorithms for use in trials to minimise the effects on

• Digital Terrestrial Television services
• licensed users of equipment for Programme Making and Special Events
• services above and below the UHF TV band.

Ofcom have also noted that whitespace availability will vary in areas across the UK i.e. London has relatively low DTT issues with whitespace use while Glasgow has much less spectrum available, however Glasgow has very little PMSE use while in central London (and areas like Wembley Stadium) there is a large amount of use.

Though it is yet early days, whitespace spectrum should allow high bandwidth services with good propagation characteristics (coverage) which could be used to provide mobile network operator capacity off-loading, broadband and machine-to-machine (M2M) services.

Companies such as Neul (a CSR - now Samsung spin-off) are betting their futures on whitespace.

The consultation closes on 15 November 2013 and stakeholders can respond on-line.

Ofcom consults on future use of 700MHz band

Ofcom , the Super regulator is holding a consultation on the future of the 700MHz band (694 - 790 MHz). This band is being used for Wireless Broadband in several countries and the EU is proposing to harmonise this band across the EU for the same purpose.

The band falls within spectrum used for Digital Terrestrial Television (DTT) also know as the UHF band IV and V which spans 470MHz through 862MHz. After the digital switchover the 800MHz band was cleared (channels 61 through 69) and this was recently auctioned off for use by mobile network for 4G/LTE services.

The lower end of the band (channels 21 through 30) starting at 470MHz is used for interleaved spectrum, local TV broadcasts (from 2013), Program making and special events (PMSE) and whitespace services (from 2014).

The band between channels 31 to 37 - the 600MHz band was cleared as part of the digital switchover.

Channel 38 is used for PMSE exclusively and now allows high power devices in the lower end of the spectrum.

The current 700MHz DTT band extends from channel 39 through channel 60 and will also be used for whitespace services from 2014.

If this spectrum is made available for mobile broadband use, it will have very good propagation characteristics and be good for rural broadband and other uses.

Though Ofcom is consulting now, the 700MHz band won't be available until 2018 at the earliest as use of the band must be in-line with International policy.

Ofcom have produced a nice picture describing the changes.

Ofcom has a duty under the Wireless Telegraphy Act 2006 to have regard to: -

• the extent to which the electromagnetic spectrum is available for use, or further use, for wireless telegraphy
• the demand for use of the spectrum for wireless telegraphy
• the demand that is likely to arise in future for the use of spectrum for wireless telegraphy.

and using the 700MHz band falls into these duties.

Unfortunately it does mean all DTT transmissions will have to move into the cleared 600MHz (channels 31 through 37) band and the lower end of the current 700MHz band (channels 39 through 48) so in 2018 there is likely to be a second TV switchover. It's also likely that set top boxes will have to use DVB-T2 and MPEG4 (rather than the less efficient DVB-T and MPEG2 that is currently used by standard definition broadcasts today, though DTT in High Definition or HD already uses DBV-T2 and MPEG4).

The full statement is on-line here and stakeholders may respond through an on-line form.

Ofcom announces Whitespace trial

Ofcom the super regulator is planning to hold a Whitespace trial later in the year. Whitespace is just spectrum that is not used in certain areas as it may interfere with other services in neighbouring areas (such as TV station broadcasts, the country is divided into areas such that neighbouring TV broadcasting transmitters don't use the same frequencies as their neighbours).

The unused spectrum is therefore 'wasted', but with careful management, can be used for localised services such as wireless broadband.

Neul is a technology leader based out of Cambridge (spun out of Cambridge Silicon Radio or CSR, now owned by Samsung) and already have systems available to use whitespace frequencies. Neul even have a chipset available for end-user devices.

There are (and have been) several whitespace trials, but these have been limited to localised technology trials.

One of the features that is required for whitespace to work is a centralised database of locations, frequencies and power levels. Generally there will be a central base station which will have to contact the database and report its position and it can then use that information to select the frequencies and power levels to use. End-user devices will just scan the whitespace bands and look for a carrier and can just use that as a base, from which it can then retrieve information about what other frequencies to use.

A quirk of the system is that Ofcom has mandated a kill switch so that if interference with commercial TV or other is found, all devices using whitespace can be shut-off in an area.

Ofcom has not specified how the database should be implemented, just the queries and responses that should be supported, it will be up to the market to decide how to implement. Database operators will be able to charge for running the service (again not specified, but it may be based on queries of the database).

This trial will again test the technology but also database implementations etc.

Ofcom's statement is on-line and any interested party wishing to take place in the trial can email TV.WhiteSpaces@ofcom.org.uk

Neul introduce witespace single chip solution

Neul, the spin off from Cambridge Silicon Radio (CSR), today announced a single chip solution for whitespace use based on their weightless standard.

The ASIC known as Iceni works across the whole UHF band (470 – 790MHz) and is easy to interface to micro-controllers and CPUs such as the ARM M3 making it ideal for M2M solutions. The chip is also small, low power and low temperature.

It can operate using both 6 or 8 MHz channels and uses daptive digital modulation schemes and error correction methods can be selected according to the trade-off between data rate and range required for a given application as well as supporting over-the-air encryption. The chip also supports programmable IO allowing it to control external parts of the solution including the RF stage and thus the transmit power (which is essential to meet any local regulations).

Neul currently dominate the whitespace arena and the technology is well suited to M2M applications - probably more sure than cellular based systems using 2G or 3G. The Neul solution can support thousands (if not more) end points and support large distances between devices (the greater the distance, the lower the bandwidth, but this generally isn't an issue for M2M installations).

Neul are conducting trials in the UK as well as other countries, however although Ofcom has made whitespace devices license exempt, it mandates a central database that contains geo-information about locations, frequencies supported and power levels. Unfortunately Ofcom have not yet implemented the central database solution.

Ofcom proposes new DTT multiplex in 600MHz

Ofcom the super regulator that covers many operations including broadcasting and spectrum allocations is proposing to open up the 600MHz band for Digital Terrestrial Television (DTT) broadcasts. The 600MHz band is actually made up of frequencies from 550-606 MHz in 8MHz channels (known as channels 31 to 37). This band was cleared when the analogue transmission services were switched off.

The new DTT service will utilise DVB-T2 and MPEG4 which allows more spectral efficiencies than older DVB-T technology and MPEG4 compresses video more efficiently than MPEG2 which current non-DS DTT services use. Program making and special events (PMSE) services will still be allowed to reside in the band as will whitespace technology (this uses localised unused spectrum to offer wireless broadband/communication services).

Ofcom is acting in accordance with EU spectrum policy, whereby the current DTT services which operate in 700MHz should move to the 600MHz band and 700MHz will be used for wireless broadband services, though migration will not happen before 2018.

Thopugh this is a proactive mode for Ofcom, many set-top boxes built for DTT will not operate in 600MHz and new systems will have to be purchased.

Ofcom is proposing to make the license available immediately at a cost of £180,000 with a minimum period until 2018 but with a 12 month notice period so Ofcom can migrate current services into this band.

The consultation is available here and interested stakeholders may respond on-line.

Ofcom opens Whitespace spectrum

Ofcom the super regulator that deals with regulation of broadcast media, radio and telecoms has made a statement about opening-up 'white space spectrum' and allow for devices to be deployed in a license exempt manner (in the UK there is no such thing as unlicensed spectrum and all transmission or reception equipment is covered by either a specific license or a 'blanket' license published by Ofcom and as long as the user/equipment abides by the conditions of the blanket license they don't need a specific license - bands like 2.4GHz which covers WiFi and Bluetooth devices are license exempt).

The equipment will have to connect to a central database (that Ofcom may actually subcontract to 3rd parties) which will note their geolocation and provide information about which frequencies are in use in that area. Ofcom may mandate a 'switch-off' mode such that if interference is detected in the area, white space devices may be forced to stop transmission.

This will be particularly suitable for rural areas as the 'white space' spectrum can be used to support wireless broadband and other services. This is significant as Ofcom are proposing that the TV bands can be used (as digital multiplexs use interleaved frequencies such that neighbouring transmitter sites don't interfere with each other) and TV bands have good propagation characteristics. Ofcom is also considering the UHF bands, though these may be more problematic longer term.

Ofcom also is considering use for WiFi like services (for localised high speed connectivity) and machine-to-machine communications which could cover things like meter reading.

Though Ofcom will have to consider European harmonisation so it make a while to implement (Ofcom is hoping for systems to be in operation by 2013), this is a bold step by Ofcom in making use of 'wasted' spectrum and being very proactive.

Ofcom will have to introduce an SI (Statutory Instrument) which is passed by Parliament to amend the WTA (Wireless Telegraphy Act) to make the spectrum license exempt.

Ofcom consultation on "whitespace" use and Gelocation

There's lots of spectrum around, but it's a crowded space and so much of it is licensed by Ofcom i.e. in order to utilise equipment that transmits or receives data in that spectrum a "use" license is required. This is why a TV license is required. Mobile phones also require a license, but that's paid as part of the license that the mobile network operators have (and have paid for).

Various parts of the spectrum have been made license exempt such as 2.4GHz which is used by WiFi (802.11b/g/n), Bluetooth and other systems like Zigbee. Licenses exempt status means that a user doesn't need to get a specific license if they use the equipment in accordance with the rules that Ofcom have published (i.e. Ofcom publish a "blanket" license and as long as the equipment in use doesn't get used outside the licensing framework, then the use doesn't need to get a license themselves). Any WiFi or Bluetooth systems will comply with Ofcom's licensing regime.

In the past Ofcom has bowed to public pressure and made certain equipment license exempt such as low power FM transmitters than can connect to MP3 and other music devices and transmit a short range to a radio (usually in a car). As they're low power, they wont interfere with the commercial radio stations (at least to other users) who have paid a lot of money for the licenses to transmit in the commercial radio bands.

Another big chunk of spectrum is in the TV bands and some of this is reserved so that interference between bands doesn't happen. The TV bands have much better propagation characteristics than say 2.4GHz which is used by WiFi and Ofcom are looking at ways of using the "dead" space for short-range low power devices which could be used say to transmit video signals between systems in the home. The whitespace could also be used for higher power rural broadband access.

They would work by looking at the bands and finding these dead areas known as whitespace and then those frequencies would be potential candidates for local transmission. However this could rapidly lead to interference between neighbouring systems (say in a neighbours house), so Ofcom wants the systems to consult a geolocation database (hosted by Ofcom) that the system could register with and ensure the whitespace was suitable for use in that area.

There would be a "master" device that would communicate with Ofcom's database and report the power and frequencies it was using and any connected devices (slaves, that wouldn't need to connect to the database themselves). The whitespace devices will be license exempt. Though Ofcom will initially run any database required, they don't evisage running the database in the future as that is best left to commercial organisations and Ofcom would like interested parties to contact them.

Though Ofcom are consulting now (the consultation runs from 09/11/10 to 07/12/10) they don't expect whitespace devices to appear until 2014.

Interested parties can respond to the consultation on-line.