LTE/ (4G) In the UK
QUESTIONS
- Q - What is Long Term Evolution (LTE)?
- Q - What is the problem?
- Q - When will it start?
- Q - When will interference start?
- Q - What is the Government Support Initiative?
- Q - How will it affect me?
- Q - How do I Mitigate the Problem?
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UK smartphone growth figures and why there is there is a demand for faster mobile broadband.
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Current Frequency Band Plan |
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LTE 800 Effects on the UHF TV Spectrum
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PMSE – Programme Making & Special Events |
The mobile equipment and the basestations use different frequency blocks. It is the downlink blocks that are the closest to the current DTT spectrum.
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The actual network of LTE transmitters will be in addition to the current services.
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The main issue is the promity of the LTE transmissions to the current DTT network and the levels of power that will be used.
Includes the Aerial, Cabling, Outlet Plates and Flyleads
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LTE Consumer mobile devices operating in the proximity of existing TVs could interfere via the Uplink Blocks with poorly screened installations and wide band amplifiers.
This includes
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- The first roll-out is planned to cover Britain’s major conurbation areas so there is not likely to be rural benefit in early stages (unless licence conditions require it).
- Everything Everywhere (EE, who own Orange and T – Mobile) have started 4G services.
- EE have been granted the use of their old 2G frequencies around 1800 MHz for 4G. This will not cause interference with DTT (but could impact some poorly screened communal satellite systems).
- Currently the Samsung S3 & I-phone 5 are compatible with the 1800 MHz LTE version (but not necessarily with the new 800MHz systems).
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Initial transmissions are planned for May.
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The role-out could take 2-3 years dependant on license agreements.
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There will be at least one-month notice period for each base station area to inform consumers that LTE transmitters will be “going-online”.
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LTE Mobile User Equipment is planned to be available prior to launch.
- Initial base Station Deployment will commence during May.
- Idle mode interference to some 6-10% of TV sets
- As mobile sales increase proximity interference to TVs will increase.
- Deployment of “fill in” Pico and Femto Cells, may invalidate previous mitigation and require extra work and cost for user.
- Interference will increase as more LTE transmitters are installed, noise floor increases and more devices become active using the 4G network
Government Support Initiative.
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Prior to the launch of the LTE transmitters the current spectrum for DTT channels 61 & 62 must be moved to allow the LTE transmissions.
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The current DTT Groups are shown below. |
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However this will change for Post DSO UHF DTT Channels
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Consideration for LTE must be made when installing products.
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This is an example of LTE interference on a DTT signal. |
Need to consider the correct use of filters Red Filter Yellow Filter Blue Filter |
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Nov 2012 - Cumbria and South West Scotland.
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March 2013 - South Wales, Parts of West and South West England
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April 2013 - Most of North West England, Halesowen in the West Midlands, the Keighley, Skipton and Cowling areas of North Yorkshire, parts of the Scottish Borders, parts of Angus, Dundee, Perth and Fife, Rosneath and the south west Highlands and Islands and Caithness.
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May 2013 - Norfolk and North Suffolk, the Salisbury area, Ventnor on the Isle of Wight the Scarborough area, South and Central Wales, North Devon, Oxfordshire, Berkshire and Buckinghamshire of the east Midlands.
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June 2013 - parts of Devon, Dorset and Cornwall.
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July 2013 parts of the Shetland and Orkney Islands, parts of north east Scotland and the Western Isle, parts of north east Scotland and the Western Isles.
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LTE transmitter role-out (from April 2013 – 2/3 years)
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Availability and growth of consumer mobile devices will include smart phones, tablets or plug-in dongles for TV and computers.
- Fitting a filter too early may stop current channels prior to clearance.
How do I Mitigate the Problem?
Prepare for a change in communication, marketing and installation techniques.
- Consider your relationship with your customer.
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Educate them to the possible issues.
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Sell the preventative measures.
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Review your terms and conditions of sale. Ensuring that you cover yourself so changes in the transmissions which could effect your installations.
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Possible change of platform to alternative platform (Freesat, Cable, Internet, etc)
Mitigating the Problem. - Retrofit Installations
- Fit LTE Filter between the aerial and the amplifier, distribution system or TV. (Which ever is first in the chain)
- Consider removal and replacement of unscreened / poorly screened components.
- - Cable, Flyleads & Outlet Plates.
- - High Gain Unscreened Mastheads.
- - Integral Aerial Amplifiers in the Dipole are unlikely to have the correct filtering. Can not filter before the amplifier.
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Fit additional filters in the system where necessary.
Mitigating the Problem. - New Systems and Installations
- Consider the “system” as a whole when preventing LTE ingress.
- All parts will contribute to a successful install.
- - Aerial.
- - Masthead Splitter/Amplifier.
- –Distribution Amplifier.
- –Cable.
- –Outlet plates.
- –Flyleads.
- –Connectors.
Mitigating the Problem: Aerials
- Forward Gain
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Increased transmitter power for DTT signals means lower gain aerials may be used.
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Consider the Out of band performance important (Traditional Designs of Yagi v Log).
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Gain is only needed for channels 21-60. Gain for the LTE blocks will only cause additional problems, so fit Group T aerials instead of WB.
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Polar Plot
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Consider any nulls in the reception.
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Response changes with frequency.
- Cross Polar Rejection.
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LTE is vertically polarised. For horizontal installation this gives at least 16 dB of rejection to the LTE signal
Mitigating the Problem: Aerials - Location of the Aerial in relation to local LTE Base Station.
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Mitigating the Problem: Aerials - Change of the Aerial Group in relation to local LTE Base Station.
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NB: Where viewers have to change the region with the new transmitter this can cause dissatisfaction in the customer. |
Mitigating the Problem: Aerials - Change of the Aerial Polarity in relation to local LTE Base Station .
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NB: Where viewers have to change the region with the new transmitter this can cause dissatisfaction in the customer. |
Mitigating the Problem: Filter
- High attenuation of the LTE bands will cure the majority of interference problems from both base stations and mobile user equipment.
- Filters will need to have higher performance for channel 57 to 60.
Mitigating the Problem: Filter - PROception : LTE Blocking Filter
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Mitigating the Problem: Filter - PROception : Splitters with LTE Blocking Filter
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Mitigating the Problem: Filter- PROception : Overlap Blocking Filter with LTE Filtering
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Mitigating the Problem: Cable, Outlet Plates and Fly-leads
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Above is a poorly screened flylead Below are screened outlets and screened flylead |
Mitigating the Problem: Measurment
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- Look at the “whole” system and try to identify the source of the interference.
- LTE CAI benchmarked aerials.
- CAI benchmarked cable.
- LTE Filters
- Fully Screened Outlet plates
- Good quality Fly leads and Connectors