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EC workshop cable TV receivers affected by new radio services in the 800 MHz band

Background. The Swiss Communication Commission

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EC workshop cable TV receivers affected by new radio services in the 800 MHz band

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    1. EC workshop cable TV receivers affected by new radio services in the 800 MHz band René Tschannen, OFCOM Brussels, 25th January 2010

    2. Background The Swiss Communication Commission „ComCom“ is planning for an auction of all mobile radio frequencies in 2010/11 (including the 800 MHz band) In this regard OFCOM held a public consultation between April and June 2009 The results of the public consultation have been published in July 2009 ? Reactions from Cable Network Operators: Concern is expressed that the introduction of mobile radio services in the 790-862 MHz frequency range would lead to interference in the cable networks and terminals connected to them (set-top boxes, TV sets, modems, etc.). The result would be intense interference in their service products (TV, radio, telephony and internet) for thousands of customers. July-August 2009: OFCOM conducted measurements and theoretical studies regarding the „IMT ? CATV“-interference issue On 9th November 2009 the Federal Communication Commission „ComCom“ instructed OFCOM to prepare the auction of mobile radio frequencies

    3. Interference immunity level for CATV-networks and –equipment EN 50083-8 “Cabled distribution systems for television and sound signals. Electromagnetic compatibility for networks” EN 50083-2 “Cable networks for television signals, sound signals and interactive services. Electromagnetic compatibility for equipment”

    4. Radiated power of mobile handsets

    5. Interference radius

    6. Measurement setups

    7. Measurement results

    8. Interference cases

    9. Findings from the measurements The wanted signal level in a CATV-network should be sufficient (e.g. >55 dBµV for a 256QAM modulated OFDM-signal) to get a reasonable C/I-ratio For use in sharing studies a realistic working level for the interfering LTE-signal is 14dBm (90th percentile value) Avoid daisy-chaining the signal through the RFin/RFout connectors of domestic equipment Use only connection cables with a good shielding effectiveness It was observed that a) interference occurs in co-channel only b) the interference radius is small (a few meters) => interference is home-made and thus under the control of the user c) the likelihood that mobile handsets radiate with high PTx levels is relatively low what reduces the risk of interference (power distribution of LTE UE) Criticism: In the view of OFCOM the measurements currently available from other parties are based on theoretical absolute worst case conditions (use of extreme PTx levels for the interferer, assumption of permanent co-channel constellations and a too low wanted signal level in the cable distribution network)

    10. Probability of co-channel interference from IMT handsets (uplink) into CATV-receivers (statistical approach)

    11. Calculating the probability of co-channel interference (statistical approach)

    12. Number of interfered CATV-receivers (statistical approach)

    13. Number of annual interferences for an individual CATV-Receiver (statistical approach)

    14. Another approach to cross-check the reliability of the statistical results („Monte Carlo“-simulation)

    15. Conclusions (1) Outcome from Measurements Interference is limited to co-channel only The likelihood that mobile handsets radiate high PTx levels is low what reduces the risk of interference The interference radius is in a range of a few meters, therefore „home-made“ and under the control of the user Outcome from Theoretical Studies Two independent theoretical approaches (statistical model & MC-simulation) have shown that the probability of co-channel interference between LTE UE and CATV-Receivers is very low Conclusion The probability of co-channel interference is a very important factor that has to be taken into account in discussions about „IMT ? CATV“-interference

    16. Conclusions (2) OFCOMs view It is politically justifiable to introduce IMT in the 800 MHz band without risking many customer complaints about interferences in CATV-networks/-devices

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