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 LTE/ (4G) In the UK

QUESTIONS 

 
What is Long Term Evolution (LTE)?
 
  • Long Term Evolution is the new protocol standard for all 4G phone systems and as its name suggests will be updated over time as new facilities are standardised.
  • As a protocol standard is not frequency dependent it will be eventually used on any and probably all of the mobile phone allocations
  • The major difference from 2 and 3G is that it is totally digital i.e. voice text and data are treated the same.
  • The DSO process has released frequency spectrum that can be used for other services.
  • Fourth Generation (4G) mobile services give fast, mobile broadband. (up to 8 Mbps)
  • World Radio Communication Conference 2007 allocated parts of TV bands IV & V for mobile applications.
    791 – 862 MHz allocated for UK.
  • In addition a new band at 2.6 GHz will be auctioned off.
  • Existing spectrum at 900, 1800 MHz and 2 GHz will convert to 4G over time.
  • 1800 MHz already in use by Everything Everywhere.
  • Released spectrum from switch to digital gives revenue for government – the ‘Digital Dividend’.
  • Government committed to faster broadband for greater number of people.

 

 
UK smartphone growth figures and why there is there is a demand for faster mobile broadband.
 
  • 4G will involve much higher power base stations
    and a large range of mobile devices. 
  • Will eventually offer rural broadband solutions.
Current Frequency Band Plan

 

LTE 800 Effects on the UHF TV Spectrum

 

  • LTE is split into separate blocks A, B & C
  • Licence may grant different operators to each block
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.

 

  • Downlink blocks 791- 821 MHz.
  • Uplink blocks 832 – 862 MHz.
 

The actual network of LTE transmitters will be in addition to the current services.

 

  • A dense network of transmitters.
  • LTE will probably use a similar network topology to that of existing 2G and 3G networks and require up to 18,000 main sites.

 


 

 

What is the problem?

 

The main issue is the promity of the LTE transmissions to the current DTT network and the levels of power that will be used.

 

  • Interference Ingress and overload to DTT reception from LTE
 

Includes the Aerial, Cabling, Outlet Plates and Flyleads

 

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

  • Internal Cabling, Outlet Plates and Flyleads.
  • Direct pick-up on TV (Move LTE Mobile Device from RF Pickup Area).
  • Communal aerial systems using private and local channels e.g. CCTV above CH 60 will suffer very bad interference.

  


 

 When will it start?

 

  • 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).
  • Initial transmissions are planned for May.
  • The role-out could take 2-3 years dependant on license agreements.
  • There will be at least one-month notice period for each base station area to inform consumers that LTE transmitters will be “going-online”.
  • LTE Mobile User Equipment is planned to be available prior to launch.

 


 

When will interference start?

 

  • 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.  

  • Digital Mobile Spectrum Limited, originally called MitCo has been required to be set up by the mobile operators as part of the auction process to action LTE related interference problems.
  • £180 million will be reserved from the auction fees to liaise with consumers and deal with the interference problems.
  • The scheme will offer a Single free filter to correct LTE inference for TVs where the DTT platform forms the primary viewing.
  • Secondary sets needing filters will need to be covered by the homeowner.
  • In certain cases, where particular TV system cannot be cured by filtering, then Freeview can be replaced with another platform (Freesat, Cable, Internet, etc)
  • History shows that the DSO Help Scheme did not gain the numbers that were forecasted for FREE upgrade.
  • Many consumers trust the local installer who is in many cases the first port of call.

 


 

How will it affect me?

 

Prior to the launch of the LTE transmitters the current spectrum for DTT channels 61 & 62 must be moved to allow the LTE transmissions.

 

  • Spectrum post-DSO and post-ch 61 & 62 clearance

 

 

The current  DTT Groups are shown below.

However this will change for Post DSO UHF DTT Channels

  • New Aerial Groups and CAI Benchmark Standards

 

Consideration for LTE must be made when installing products.

 

  • Unhappy customers with interference on their TV(s), caused by an unreliable DTT signal.
  • LTE interference will be very well publicised but many people will take no notice until TV signal becomes a problem.  Installations prior to LTE without filtering also need to be considered.
  • Possible > 2 million households affected
  • Opportunity to increase business post DSO.

  • Retro-fit existing installation with LTE filters, good cable, flyleads, outlet plates etc.

  • New installations consider correct choice of

         - Aerial

         - Splitter / Amplifier

         - Cable

         - Outlet Plate/Fly lead

         - Filter - Warning!! - Filters have a loss and Filters fitted by the general public may affect their TV reception. Allow for filter loss in your signal budget.

 

 

This is an example of LTE interference on a DTT signal.

 

Need to consider the correct use of filters

Red Filter
Passes 58 with 3dB of insertion loss  45dB rejection of LTE A

Yellow Filter
Higher cost to pass 59/60 & reject LTE A

Blue Filter
Traditional  Filter Design (Not Suitable)

 

The Channel 61:62 Clearance Retune Events 2012-2013 is list below.
 
  • Nov 2012 -  Cumbria and South West Scotland.
  • March 2013 - South Wales, Parts of West and South West England
  • 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.
  • 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. 
  • June 2013 - parts of Devon, Dorset and Cornwall. 
  • 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.
 
Full details of the clearance plan is online at www.digitaluk.co.uk/transmitternetwork/clearanceevents.
 
Timeframes to potential interference
 
  • LTE transmitter role-out (from April 2013 – 2/3 years)
  • 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.
  • Educate them to the possible issues.
  • Sell the preventative measures.
  • Review your terms and conditions of sale. Ensuring that you cover yourself so changes in the transmissions which could effect your installations.
  • 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.
  • 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
  • Increased transmitter power for DTT signals means lower gain aerials may be used.
  • Consider the Out of band performance important (Traditional Designs of Yagi v Log).
  • 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.

 

  • Polar Plot
  • Consider any nulls in the reception.
  • Response changes with frequency.

 

  • Cross Polar Rejection.
  • LTE is vertically polarised. For horizontal installation this gives at least 16 dB of rejection to the LTE signal

 

Use LTE CAI Benchmarked Aerials and correct New Groups – T and A.
 

Mitigating the Problem: Aerials - Location of the Aerial in relation to local LTE Base Station.

 

  • Consider location of the aerial. Can it be re-sited on the same building but using the building, surroundings or local topology as a screen?
  • Aerials mounted high on the chimney versus a lower gable end installation.

Mitigating the Problem: Aerials - Change of the Aerial Group in relation to local LTE Base Station.

 

  • With increased powers from TV transmitters, consider if there are alternative transmitters to receive the DTT signals. Redirection and repositioning of the aerial may reduce the LTE interference. Fitting an aerial to receive DTT signals from a distant alternative transmitter may now be possible.
  • If the alternative transmitter uses lower channel frequencies such as a group A or B then the level of attenuation required by the filter will be reduced.

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

.

  • If the LTE base transmissions are vertical only. If possible choose a horizontal transmission. Fitting an aerial to receive DTT signals from a distant alternative transmitter may now be possible
  • The cross polar protection from the aerial will assist with the Vertical LTE interference.

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

 

  • Four models available proLTE1/57C, proLTE1/57F, proLTE1/57FLY and proLTE2/57F

  • Passes all terrestrial broadcast transmissions up to and including TV channel 57.

  • High attenuation in LTE bands. Will cure the majority of interference problems, from both base stations and mobile user equipment. 35dB-55dB

  • Low insertion loss and good 75 Ω match throughout the pass-band.

  • Choice of either IEC or F-type connectors with good screening factor, helping prevent leakage around the filter.

  • Male and female connectors allow insertion into existing systems with no need for further cables or back-to-back adapters.

  • Power-pass: this is a pure low-pass filter and passes AC and DC line-power.

  • Inline Versions have waterproof housing, suitable for outdoor applications when used with suitable mating F connectors. (Rated to IP55).

  • The Fly lead version is ideal for fitting at the back of a TV with low profile or in difficult access areas.

  • Masthead version includes weatherproof case and tie fixings.

  • All have Power pass rating 24 V and 250 mA max.

 
PROLTE2/57F  
PROLTE1/57FLY  

 

Mitigating the Problem: Filter - PROception : Splitters with LTE Blocking Filter

 

  • Two models available proLTE12/57 and proLTE14/57
  • 2-, and 4-way models available.Passes all terrestrial broadcast transmissions up to and including TV channel 57.
  • High attenuation in LTE bands, will cure the majority of interference problems, from both base stationsand mobile user equipment.
  • Low insertion loss with excellent 75 Ω impedance matching and high isolation between outputs.
  • Fully screened RF modules in robust diecast enclosures. Strong cast-in 'F' connectors.
  • Proven free-draining moulded enclosures give easy access and cannot trap water.
  • Directional power pass (20 V & 250 mA max) from any output leg to the common input, allowing an upstream amplifier to be powered.
  • Low insertion loss and good 75 Ω match throughout the pass-band.
  • Male and female connectors allow insertion into existing systems with no need for further cables or back-to-back adapters.
  • With equipotential bonding point..
 proLTE14/57
PROLTE12/57

 

 

Mitigating the Problem: Filter- PROception : Overlap Blocking Filter with LTE Filtering

 

  • Four models available proOBF1A, proOBF1B, proOBF1C and proOBF1E
  • UHF bandpass filters intended for blocking unwanted reception of transmissions from an adjacent region.
  • Optimised passbands cover most UK requirements in just four versions.
  • Good out-of band rejection helps block TETRA and GSM, also LTE (4G), depending on model. e.g. proOBF1A for CRYSTAL PALACE
  • Typical stopband rejection is around 35–40 dB except close to the band edges.
  • Good 75 Ω match throughout the passband.
  • Optional weatherproof outdoor housing available (order product code proMHD/CASE/S).
    .
 
 

 

 

Mitigating the Problem: Cable, Outlet Plates and Fly-leads

 

  • Fit ONLY high quality cables. The use of CAI benchmarked cables with additional high quality screening is recommended.

 

  • ONLY fit outlet plates that conform to the EMC standard EN50083-2.

 

 

 

Above is a poorly screened flylead

Below are screened outlets and screened flylead

 

Mitigating the Problem: Measurment

 

  • Meter Measurement of LTE
  • New meter/new software offers Filtering Analysis
 

 

Mitigating the Problem: Conclusions
 
  • 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
Further information on LTE and Mitigation is available on the CAI website here