DTTB Frequency Planning

Transcription

1 DTTB Frequency Planning Apprach and chices made in develping the DTTB frequency plan in Thailand ITU/NBTC Wrkshp 4 December 2014 Jan Deven

2 DTTB frequency planning Tpics 1. Frequency plan Spectrum management principles Different scenaris Cntent f a plan 2. Planning principles Spectrum requirements Receptin mde Service trade-ff Single Frequency Netwrks Reginal cverage Presentatin f results 3. Data and tls Databases and planning sftware 4. Planning prcess Planning sequence Planning steps 2

3 1. Frequency plan 1.1 Spectrum management principles Frequency assignment principles Characteristic A-priry plan Knwn service areas N unacceptable interference Future requirements Flexibility regarding unfreseen develpments First cme first served Nnprtectin basis yes yes n yes yes n yes limited yes limited limited yes A-priry plan giving bradcasters and NOs certainty fr a lng perid maintaining high quality receptin levels in cverage areas described at mment f licensing 3

4 1. Frequency plan 1.2 Spectrum management principles Frequency planning cncept Example Frequency re-use distance Specifying transmitting statins (frequency, pwer, antenna height) in such a way that The required cverage is achieved While interference is kept t an acceptable level In DTTB: interference means n picture Interference taken int accunt if sites are separated: < 400 km acrss land <650 km acrss sea 4

5 1. Frequency plan 1.3 Different scenaris A frequency plan related t the transitin frm analgue TV (ATV) t digital televisin (DTTB) cnsists f three stages Stages VHF plan UHF plan Befre DTTB launch During transitin After ATV switch-ff ATV ATV Mbile ATV ATV DTTB Mbile DTAB DTTB Mbile Scenari A 5 transmitters per site First deplyment phase with 11 sites Scenari B 5 transmitters per site During transitin Temprarily channels t avid interference with ATV Scenari C 6 transmitters (multiplexes) per site After ATV switch-ff 5

6 1. Frequency plan 1.4 Cntent f a plan List f transmitting statin characteristics Example Site Chiang Mai Lng Lat Site name and crdinates Site and antenna height Effective radiated pwer (ERP) Antenna pattern Channel r frequency Netwrk Netwrk Ch Sc C Ch Sc B NBT Army TV MCOT TPBS Army TV Cmm. TV 34 - ERP 50 kw Directinal antenna pattern 39 main sites 132 additinal sites t supplement cverage f main sites, cnsisting f 45 exiting TV sites 38 telecm sites 49 new sites 15 gap-fillers in Bangkk t imprve indr receptin 6

7 2. Planning principles 2.1 Spectrum requirements Internatinal crdinatin Internatinal and natinal spectrum regulatins Equitable access f the spectrum t all cuntries Crdinatin agreements with neighbring cuntries Internatinal frequency allcatins in Asia-Pacific area in UHF band 470 MHz Bradcasting Mbile Bradcasting Mbile (IMT) Ch Ch MHz Frm 2015 Each cuntry shuld decide n the natinal applicatins 862 MHz Within 100 km frm Malaysian brder use f even numbered channels DTTB in UHF band Channels 26 t 60 7

8 2. Planning principles 2.2 Receptin mde Rftp receptin Directinal antenna n the rf Receptin height in planning: 10 m Antenna bearing and channel range culd be different cmpared t analgue TV Antenna replacement may be needed fr gd DTTB receptin Requirement t cver 95% f the husehlds with rftp receptin Assuming well lcated receiving antenna f gd quality Use f antenna amplifier were needed Planning results indicate fr each receiving lcatin the best DTTB transmitter 8

9 2. Planning principles 2.3 Receptin mde Indr receptin Indr receptin requires much higher signal strength than rftp receptin Small antenna in the rm Receptin height in planning: 1.5 m Fr same cverage as rftp receptin 16,000 x mre transmitted pwer needed Indr receptin in many twns due t clse lcatin f sites Abut 40% husehlds with gd indr receptin 15 gap-filler in Bangkk t imprve indr receptin 9

10 2. Planning principles 2.4 Service trade-ff Capacity, cverage and transmitted pwer are interrelated Service trade-ff DVB-T2 system variant Ptential viewers Size f cverage area Mre capacity mre pwer needed r smaller cverage area Mre suitable fr indr and mbile receptin less capacity Site characteristics Mre pwer and higher antenna larger cverage Netwrk csts Transmitter pwer and number f sites Service quality Transmissin capacity After extensive studies and field tests by NOs, DVB-T2 system variant selected (16k, 64QAM, 3/5, PP2) prviding: Mid range capacity f abut 22 Mbit/s per transmitter Fairly rbust indr receptin pssibilities 10

11 2. Planning principles 2.5 Single Frequency Netwrks (SFN) Use f SFN where pssible Example Self-interference reslved by means f artificial delay and mdified antenna patterns The cntent f the transmissin must be the same at all sites in a SFN Use f SFN is limited by self-interference Red: Selfinterference Remaining selfinterference utside cverage area Guard-interval f selected DVB-T2 variant is 266 µs If transmitter distance in SFN is > 79.8 km selfinterference may ccur, depending n C/I rati 127 f the 132 additinal sites are part f a SFN All 15 gap-fillers in Bangkk in SFN In ttal 48 SFNs 11

12 2. Planning principles 2.6 Reginal cverage Sme SFNs cver mre than ne reginal area Example SFN with 3 sites in cmmunity TV area 2 and 1 site in cmmunity TV area 1 Site in a different reginal area than the ther sites in the SFN shuld transmit different services Site NBT CTV Decupled frm SFN t enable transmissin f different services Different channel needed (excluding it frm the SFN) 5 netwrks with natinal services 1 netwrk with services fr each f 39 cmmunity TV areas 12

13 2. Planning principles 2.7 Presentatin f results Receptin prbability in a small area (100 by 100 m) Example Cverage presentatin Receptin prbability in %, taking int accunt: Field strength f wanted signal Field strength f interfering signals Minimum median field strength (Emed) and prtectin rati accrding t ITU-R recmmendatins Orange: 95% Yellw:90-95% Green: 70-90% Receptin prbability 95%: gd receptin 90-95%: gd receptin with well lcated antenna f gd quality 70 90%: fr infrmatin Wanted signals 50% f time Interference 1% f time 13

14 3. Data and tls 3.1 Databases and planning sftware Accurate cverage predictins require detailed data and advanced planning sftware Digital terrain databases Terrain height Land use (clutter) type and height Ppulatin database Site data Peple r husehlds per small area unit Accurate crdinates, antenna heights and antenna data (if apprpriate) f existing sites Backgrunds maps Detailed infrmatin n terrain and urban areas Terrain height and clutter data reslutin 100 by 100 m in whle cuntry 20 by 20 m in Bangkk Ppulatin database Ppulatin and husehlds per tambn Backgrund maps Bing maps and Ggle Earth Planning tl Prgira plan 14

15 4. Planning prcess 4.1. Planning sequence Original DTTB plan 39 main sites after ASO 39 main sites during transitin 15 gap-fillers Bangkk Analysis f riginal plan T be reviewed due t new requirements and chice f DVB-T2 system variant Planning f 39 main sites ptimized fr the situatin after analgue TV switch-ff Scenari C Planning f 39 main sites befre analgue TV switch-ff, based n scenari C Scenari B and A Verificatin f planning f 15 gap-fillers in Bangkk Scenari C and B Planning main sites befre additinal sites: First cmefirst served principle Planning f additinal sites in such a way that main sites are nt unacceptably interfered Additinal sites Planning f additinal sites t reach cverage target f 95% husehlds Scenari C 15

16 4. Planning prcess 4.2 Planning steps Netwrk tplgy Initial channel assignments Cmpatibility analysis Specificatin f lcatin and initial ERP and antenna f sites Accrding t best practices One channel per site (mid channel) Main challenge was t reach the cverage target f 95% husehld cverage per netwrk 4 5 Detailed SFN/MFN planning Cmpatibility and cverage check Reslving interference All channels per sites Checking n errrs r missins Review f ERP t ptimise cverage Cverage calculatins and presentatin f results 16