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Compatibility of Digital Broadcasting and Mobile Services

or. Where’s my picture gone?. Regional Seminar on Digital TV Broadcasting Algiers, 4-5 December 2007. Compatibility of Digital Broadcasting and Mobile Services. Presented by Jan Doeven. 1. Analogue TV transferred to digital. Band IV/V spectrum. Digital dividend.

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Compatibility of Digital Broadcasting and Mobile Services

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  1. or Where’s my picture gone? Regional Seminar on Digital TV Broadcasting Algiers, 4-5 December 2007 Compatibility of Digital Broadcasting and Mobile Services Presented byJan Doeven 1

  2. Analogue TV transferred to digital Band IV/V spectrum Digital dividend Concerns about Digital Dividend • Interference scenarios • Non-co-sited transmitters • Moving interferencesources • Cross border interference • Digital TV receiver • Selectivity • Channel interactions If part of theDigital Dividend is allocated to mobile communication services,black screens could be expected. 2

  3. Non co-sited transmitters:The issue Non co-sited transmitters are increasingly used because of: Different network operators for the same type of service Different network structures for different service types The interference is mainly localized around the interfering transmitter site 3

  4. Non co-sited transmitter Channel N+x Where’s my picture gone? Maximum acceptable difference between wanted and unwanted signals Interfering field strength Service area Interference area Non co-sited transmitters: Coverage gaps Wanted DVB-T transmitter Channel N Wanted field strength Field strength Distance

  5. Non co-sited transmitters: The solution • Careful planning using mitigation techniques: • Interference between non co-sited transmitters is an issue, but still is manageable through careful planning 5

  6. Moving interference sources: The issue • Mobile communication systems: • The Downlink is technically similar to broadcasting and therefore can be controlled • The Uplink is initiated from moving terminals and therefore can not be controlled Radiated energy : Hand-held to DVB Mobile hand-held DVB-T receiver 6

  7. Portable reception Portable or rooftop reception Portable (indoor and outdoor) possible in limited area because of high required field strength Rooftop reception Moving interference sources:Portable –indoor and outdoor- reception • Each GE06 Plan entry has a specified reception mode

  8. Moving interference sources: New convenient reception modes Where’s my picture gone? • Portable antennas • Indoor reception • USB stick receivers • Hand-held receivers • Mobile in-car receivers • Portable and mobile reception can be exposed to interference from mobile uplinks • at very short distances (few metres) 8

  9. Band partitioning, with: Sufficient guard bands Adequate maximum transmitting power Sufficiently low out of band emissions Moving interference sources: Thesolution Guard band 9

  10. Cross border interference:to the Mobile service! Uplink reception at Base station is very sensitive Sub-band use is not mandatory, Neighbouring country may continue to use high power broadcasting transmitters in the same sub-band Cross border coordination becomes very difficult 10

  11. Interfering Radiated energy : DVB to Base station DVB-Ttransmitter Channel N Cross border interference:The issue Country B Country A Base station receiver Channel N Radiated energy : Hand-held to Base station Where’s my picture gone? Mobile hand-held tx

  12. The digital receiver • Receiver selectivity • Channel interactions

  13. Average values of 7 DVB-T receivers64QAM 2/3 C/I (dB) Receiver selectivityOverloading and N+9 issues Channel offset Source: BBC

  14. Receiver selectivityPerformance • Out of band protection ratios below specifications under normal operating conditions • Specifications exceeded in case of overloading. • In order to improve compatibility out of band performance need to be improved.

  15. N+9 DVB-T channel where there could be N+9 interference on some receivers if overloaded Channels interactions:some band-plan examples Guard band or duplex gap (between Downlink and Uplink)

  16. CONCLUSIONS Careful planning is needed to avoid interference between non co-sited transmitters; DVB-T transmitters and mobile base stations. Interference from mobile uplink transmissions could be an issue even with sub band operation; Needs careful investigations. Use of same channel by DVB-T and Mobile uplinks will in borders areas will give severe restrictions to mobile service. Improved digital receiver performance with regard to interference is required; In particular in case of overloading. 16

  17. To know more about why your picture is gone…. ..and what could happen if any Digital Dividend is spent unwisely? Watch the video at www.ebu.ch

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