Compatibility measurements UMTS/LTE/GSM -> GSM-R Thomas Hasenpusch Federal Network Agency, Germany CG-GSM-R(13)033

2 Motivation / Aims Frequency planning in Europe: What happens to the GSM-R terminal receivers when facing UMTS/LTE in the public mobile band above 925 MHz? GSM-R compatibility measurements (BnetzA Germany)

3 Interference Mechanisms (1) Unwanted emissions from UMTS/LTE in the GSM-R channel A f 925 MHz GSM-R channel GSM-R compatibility measurements (BnetzA Germany)

4 Interference Mechanisms (2) Receiver blocking due to high input powers A f Min. S/N Max. mixer power GSM-R compatibility measurements (BnetzA Germany)

5 Interference Mechanisms (3) Receiver intermodulation (2 narrowband signals) A f GSM-R channel f1f1 f2f2 f IM f IM = 2*f 1 -f 2 GSM-R compatibility measurements (BnetzA Germany)

6 Interference Mechanisms (4) Receiver intermodulation (1 wideband signal) 921.2MHz 924.8MHz UMTS GSM UMTS signal IM products (all) IM frequencies involved when GSM-R frequency is MHz IM frequencies involved when GSM-R frequency is MHz GSM-R compatibility measurements (BnetzA Germany)

7 Interfering GSM Signals GSM-R compatibility measurements (BnetzA Germany)

8 Interfering UMTS signals GSM-R compatibility measurements (BnetzA Germany)

9 Interfering LTE/5MHz signals GSM-R compatibility measurements (BnetzA Germany)

10 Receiver Selection Rx1 „improved“: Receiver with highly linear front- end, improved filter and AGC, exceeding requirements of ETSI TS Rx2 „standard“: Receiver representing equipment currently used in trains, meeting requirements of ETSI EN V8.5.1 and ETSI TS V8.16 GSM-R compatibility measurements (BnetzA Germany)

11 Failure Criterion The GSM-R link was regarded interfered when the RxQual value reported by the terminal receiver dropped to 4 or less. Measured with CMU200 base station tester. GSM-R compatibility measurements (BnetzA Germany)

12 Measurement of Receiver Characteristics Sensitivity of both receivers: -107 to -108 dBm Selectivity (measured with unmodulated carrier): GSM-R compatibility measurements (BnetzA Germany)

13 C/I from Unwanted Emissions Measurement setup: GSM-R base station emulator CMU dB GSM-R receiver (DUT) M downlink uplink Rx Tx Circulator (10) Directional coupler 20 dB 50 dB Signal generator Interfering signal 6-60 dB GSM-R signal level: -101 dBm and -98 dBm GSM-R compatibility measurements (BnetzA Germany)

14 C/I from Unwanted Emissions Measurement results for standard interferers: GSM-R compatibility measurements (BnetzA Germany)

15 C/I from Unwanted Emissions Measurement results for realistic interferers: GSM-R compatibility measurements (BnetzA Germany)

16 C/I Using Blocking Test Setup: Measurement setup: GSM-R base station emulator CMU dB GSM-R receiver (DUT) M downlink uplink Rx Tx Circulator Directional coupler 20 dB 50 dB Signal generator Interfering signal 6-60 dBBand pass GSM-R frequencies MHz and MHz GSM-R signal levels between -101 and -35 dBm 3 different interfering frequencies, but always high offset GSM-R compatibility measurements (BnetzA Germany)

17 C/I Using Blocking Test Setup Measurement results for GSM interferer: GSM-R compatibility measurements (BnetzA Germany)

18 C/I Using Blocking Test Setup Measurement results for broadband interferer: GSM-R compatibility measurements (BnetzA Germany)

19 C/I Using Intermodulation Test Setup Measurement setup: GSM-R base station emulator CMU dB GSM-R receiver (DUT) M downlink uplink Rx Tx Circulator (10) Directional coupler 20 dB 50 dB Signal generator 1 Interfering signal 6-60 dBBand pass Signal generator Ω GSM-R compatibility measurements (BnetzA Germany)

20 C/I Using Intermodulation Test Setup Frequency combinations: Signal 1Signal 2 CombinationSystemFrequency f 1 SystemFrequency f 2 1GSM935,0 MHzGSM948,8 MHz 2GSM935,0 MHzUMTS947,5 MHz 3UMTS937,5 MHzGSM953,8 MHz 4LTE/10MHz935,0 MHzUMTS942,5 MHz 5UMTS937,5 MHzUMTS952,5 MHz 6GSM927,4 MHzUMTS932,5 MHz GSM-R compatibility measurements (BnetzA Germany)

21 C/I Using Intermodulation Test Setup Measurement results GSM-R compatibility measurements (BnetzA Germany)

22 Combination of Results One single GSM interferer GSM-R compatibility measurements (BnetzA Germany)

23 Combination of Results One UMTS interferer: GSM-R compatibility measurements (BnetzA Germany)

24 Combination of Results One LTE/5MHz interferer: GSM-R compatibility measurements (BnetzA Germany)

25 Combination of Results Two or more GSM interferers: GSM-R compatibility measurements (BnetzA Germany)

26 Combination of Results UMTS interferer plus UMTS/GSM interferer: GSM-R compatibility measurements (BnetzA Germany)

27 Result Evaluation (1) At low GSM-R levels unwanted emissions dominate, at higher GSM-R levels receiver overloading dominates. Transition between interference effects strongly depends on interfering signal quality: Realistic signals have much less interference potential from unwanted emissions than signals just meeting the standard. The interference potential of UMTS and LTE/5MHz is nearly equal. Interference potential due to unwanted emissions from UMTS/LTE is about dB higher than from GSM. One UMTS/LTE signal alone may create receiver intermodulation often affecting the whole GSM-R band. GSM-R compatibility measurements (BnetzA Germany)

28 Additional Measurements with Filters Necessary to assess: GSM-R on upper channels, UMTS/LTE in first 5MHz of public band (critical situations) Improvements by different receiver filter solutions Receiver configurations: Rx1: „improved“ Rx2: „standard“ Rx3: „standard“ receiver plus dual 8-cavity Kaelus filter Rx4: „improved“ receiver plus small Lorch filter GSM-R compatibility measurements (BnetzA Germany)

29 Additional Measurements with Filters Filter response dual 8-cavity Kaelus (1): GSM-R compatibility measurements (BnetzA Germany)

30 Additional Measurements with Filters Filter response dual 8-cavity Kaelus (2): GSM-R compatibility measurements (BnetzA Germany)

31 Additional Measurements with Filters Filter response low pass Lorch (1): GSM-R compatibility measurements (BnetzA Germany)

32 Additional Measurements with Filters Filter response low pass Lorch (2): GSM-R compatibility measurements (BnetzA Germany)

33 Additional Measurements with Filters Measurement setup: GSM-R base station emulator CMU dB GSM-R receiver (DUT) incl. filter for Rx3 and Rx4 M downlink uplink Rx Tx Circulator (10) Directional coupler 20 dB 50 dB Signal generator SMU200A Interfering signal GSM-R frequencies MHz and MHz GSM-R levels from -101 dBm to -31 dBm Interfering frequencies MHz and MHz (UMTS/LTE) and MHz (GSM) GSM-R compatibility measurements (BnetzA Germany)

34 Additional Measurements with Filters Result example (realistic broadband interferer): GSM-R compatibility measurements (BnetzA Germany)

35 Additional Measurements with Filters Result example (standard broadband interferer): GSM-R compatibility measurements (BnetzA Germany)

36 Additional Measurements with Filters Result example (realistic interferer on MHz): GSM-R compatibility measurements (BnetzA Germany)

37 Additional Measurements with Filters Result example (standard interferer on MHz): GSM-R compatibility measurements (BnetzA Germany)

38 Additional Measurements with Filters Result example (realistic interferer vs. channel 970): GSM-R compatibility measurements (BnetzA Germany)

39 Additional Measurements with Filters Result example (standard interferer vs. channel 970): GSM-R compatibility measurements (BnetzA Germany)

40 Additional Measurements with Filters Result example (GSM realistic interferer): GSM-R compatibility measurements (BnetzA Germany)

41 Additional Measurements with Filters Transition levels from unwanted emissions to overloading effects InterfererRx1 (improved) Rx2 (standard) Rx3 (standard with Kaelus filter) Rx4 (improved with Lorch filter) UMTS realistic on MHz -80 dBm-100 dBmnever *)-80 dBm LTE realistic on MHz -85 dBm-98 dBmnever *)-85 dBm UMTS standard on MHz -48 dBm-72 dBmnever *)-45 dBm LTE standard on MHz -52 dBm-78 dBmnever *)-50 dBm UMTS realistic on MHz never *)-100 dBmnever *)- LTE realistic on MHz never *)-100 dBmnever *)- UMTS standard on MHz never *)-85 dBmnever *)- LTE standard on MHz never *)-90 dBmnever *)- GSM realistic on MHz -90 dBm-80 dBm -88 dBm GSM standard on MHz -85 dBm-75 dBm-72 dBm-82 dBm *) never = not overloaded up to about +10 dBm GSM-R compatibility measurements (BnetzA Germany)

42 Result Evaluation (2) The standard receiver is nearly always overloaded by UMTS/LTE in the first 5 MHz of the public mobile band. The improved receiver is only overloaded when UMTS/LTE is on MHz and the GSM-R level is high (>80dBm for realistic, >50dBm for standard signals), and then the tolerable interference level is up to 20 dB higher than for the standard receiver. Receivers with the Kaelus filter are never overloaded by UMTS/LTE signals. The additional Lorch filter for the improved receiver does not further increase immunity against UMTS/LTE on MHz. GSM-R compatibility measurements (BnetzA Germany)

Compatibility measurements UMTS/LTE/GSM -> GSM-R Thomas Hasenpusch Federal Network Agency, Germany / ECC Thank you for your attention!