ATDI Consulting ATDI Software. Single Frequency Networks (SFN) with ICS Telecom V9

Transcription

1 ATDI Consulting ATDI Software Single Frequency Networks (SFN) with ICS Telecom V9

2 Introduction OFDM Analogue Planning SFN systems in ICS Telecom FM Quasi-synchronise Paging DAB Digital Radio DVB T Digital Video Broadcasting DVB-H Digital Video Broadcasting - Handheld

3 1 s 300m Wanted and Un-Wanted Paths 15 s 10 s 5 s TOA (wanted) TOA (unwanted) C/I requirement is related to difference between TOA (for FM Broadcast ITU-R BS table 5) 5 s 10 s 15 s 20 s

4 Characteristics of FM Quasi-Sync Networks (Analogue) Main sites Generally high power omni type antennas Fill in sites Low power directional antennas) - Used to fill in gaps in coverage Demonstration Design Quasi-Sync network to cover defined service area Calculate the amount of interference in the service area (SFN) Maximise the coverage of the required service area Calculate the interference due to MFN Calculate the area interfered MFN & SFN

5 Analogue Quasi Synchronous Systems

6 - Simulcast interference best server Displays SFN interference and best server - Simulcast interference max FS Displays max field strength and interference (Constructive field strength adds FS together If delta TOA < delta TOA threshold power sum) - Time of Arrival of each server indicates the delta TOA between signals - Launch delay assignment assigns launch delay to minimise interference (note over all modelling area or within extd radius) TOA delta = time delay between signals Percentage = percentage of interfering power seen by wanted signal C/I = Protection ratio required for given delta TOA

7 Investigate areas of Interference Point investigation shows the field strength of all wanted signals above the threshold level and all known interferers Demonstration:

8 Example Demonstration SE UK Sync-network North London to serve A1 (M) Maximise coverage of Motorway area % of required area interfered SFN % of required area interfered MFN % of required area interfered MFN & SFN

9 Any Questions on Analogue Quasi Synchronous calculations?

10 Digital Single Frequency Networks OFDM network only T-DAB & DVB networks Interference can depend on synchronisation strategy used ICS Telecom has 3 Synchronisation Strategies it can apply: Strongest signal First signal (above threshold) First Server Best Sever - Margin

11 First signal Relative Amplitude Signal 1 Signal 4 Signal 3 Signal 5 Signal 2 Strongest signal Relative Amplitude Signal 1 Signal 4 Signal 3 Signal 5 Signal 2 Synchronisation Strategies = Inter symbol interference Signal 1 Signal 2 Signal 3 Signal 4 Signal 5 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Time FFT Window Signal 1 Signal 2 Signal 3 Signal 4 Signal 5 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 Symbol n-1 Symbol n Symbol n-1 FFT Window

12 Other synchronisation methods currently not available in ICS Telecom Centre of Gravity (for future development) Quasi-optimal Maximum C/I Which synchronisation method used by the receiver is not specified in standards, hence manufacturers choose? Therefore when modelling will need to test both ATDI options

13 OFDM SFN Calculation

14 DVB for different modulation coding and guard intervals DAB has a number of country specific transmission modes (I, II, III and IV). For worldwide operation a receiver must support all 4 modes: Mode I for Band III, Earth (174 to 230MHz) Mode II for L-Band, Earth and satellite (1-2GHz) Mode III for frequencies below 3 GHz, Earth and satellite Mode IV for L-Band, Earth and satellite (1-2GHz) ProfP parameters for WiMAX systems

15 Radio propagation prediction in multipath environments If using a high resolution DEM or DSM the multipath environment can be modelled Reflection coefficient Where maximum delta TOA is the total symbol duration (DVB-H 2K¼ ) Margin is co-channel protection (DVB-H QPSK Rayleigh) Synchronisation threshold is the dbuv/m level above the noise floor required for sync

16 Wanted / Unwanted coverage How receiver synchronisation is applied Guard interval & symbol size Progressive destructive FS - then signal destructive if TOA or TOA > guard interval Signal not summed if in guard interval Sync level KTBF + Margin

17 Demonstration SFN Network Best server C/I+N First server C/I+N With un-wanted coverage With directional antenna With Other changes to window function % locations calculation Best server Also Investigation on why interference is occurring Population calculation Site searching

18 Thankyou for Attending This webinar covers most of the features for Single frequency networks within ICS Telecom and HTZ Warfare Any Questions? FUTURE EVENTS Webinars will resume in September 2010 Visit for more information

19 ITU-R BS412-9 References EBU Guide on SFN Frequency planning and network implementation with regard to T-DAB and DVB-T ATDI white paper DVB-H radio planning aspects in ICS Telecom ATDI White paper DVB-H network design Final Acts of CEPT T-DAB planning meeting Constanta 2007 ITU RRC-06 planning of digital terrestrial broadcasting service in parts of regions 1 and 3 in the frequency bands MHz and MHz

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