Regional Information Meeting and Workshop related to the RRC-06 for the administrations of the African countries Dakar, Senegal, April 2005 Planning for DVB-T and T-DAB services Some practical considerations Pham Nhu Hai Radiocommunication Bureau

RRC information meeting and workshop Dakar, Senegal April 2005 Outline Digital world! Policy objectives Planning objectives Planning methodology

RRC information meeting and workshop Dakar, Senegal April 2005 Digital world! DVB-T and T-DAB based on completely different techniques –Large number of carriers –Several programs bundled into multiplexes. Each multiplex T-DAB: 6 to 8 programs DVB-T: 2 to 4 PAL equivalent programs

RRC information meeting and workshop Dakar, Senegal April 2005 Digital world!! Brick wall reception effect (4 to 1: 2dB)

RRC information meeting and workshop Dakar, Senegal April 2005 Digital world!!! Reception modes –Fixed –Portable indoor –Portable outdoor –Mobile

RRC information meeting and workshop Dakar, Senegal April 2005 Digital world!!! Single Frequency networks (SFN)

RRC information meeting and workshop Dakar, Senegal April 2005 Policy decisions - examples Conversions –Can all broadcasters convert? –Same coverage between digital and analogue? –Simulcast? How long? Competition –New players in the market –How many? –When new licences issued?

RRC information meeting and workshop Dakar, Senegal April 2005 Policy decisions – more examples Equalisation –Same number of services throughout the country? –More in urban centres? Spectrum for other uses –Which parts of the frequency bands? –When and How?

RRC information meeting and workshop Dakar, Senegal April 2005 Planning objectives? Simulcast of analogue and digital Digital = analogue coverage as soon as possible Portable reception modes in urban centers and fixed for outskirt areas Quality of service – High definition? Number of services

RRC information meeting and workshop Dakar, Senegal April 2005 Frequency bands? MHz –DVB-T and T-DAB –T-DAB only –DVB-T only –Mixed TV channel spacing MHz –Whole bands –Part of the bands

RRC information meeting and workshop Dakar, Senegal April 2005 Which reception mode? DVB-T –Fixed –Portable outdoor and indoor –Mobile –Main population – portable –Outlying areas - Fixed T-DAB –Mobile –Portable indoor

RRC information meeting and workshop Dakar, Senegal April 2005 DVB-T system variants? Fixed reception –64QAM and 2/3 code rate 1/8 guard interval –16QAM and 2/3 code rate 1/8 guard interval Mobile reception –8K QPSK 2/3 rate and ¼ guard interval –2K 16QAM ½ rate and ¼ guard interval Use RPCs

RRC information meeting and workshop Dakar, Senegal April 2005 Network structure? Multi Frequency Network (MFN) Single Frequency Network (SFN)

RRC information meeting and workshop Dakar, Senegal April 2005 Multi frequency network MFN Each transmitter operates on a different frequency Overlaps between transmitters possible Regional or local programming Ideal for conversion of existing analogue services

RRC information meeting and workshop Dakar, Senegal April 2005 Single frequency network SFN All transmitters operates on the same frequency and carry the same program Ideal for national or large regional networks Low power transmitters can be added if required Most suited for mobile networks

RRC information meeting and workshop Dakar, Senegal April 2005 Planning criteria Minimise interference and disruption to analogue services Minimise cost to viewers and broadcasters –Use of existing transmitting facilities –Consideration of existing receive antennas Identify a minimum of N channels

RRC information meeting and workshop Dakar, Senegal April 2005 One planning approach Determine minimum median field strength –System variants –Reception mode Determine ERP required to provide desired coverage –Propagation models –Tx site –Receive antenna

RRC information meeting and workshop Dakar, Senegal April 2005 One planning approach.. Calculate available protection ratio APR=W-U+AD+PD Where W: wanted signal level (dBuV/m) U: unwanted signal level (dBuV/m) AD: antenna directivity (dB) PD: polarisation discrimination (dB) Use knowledge from existing analogue situation

RRC information meeting and workshop Dakar, Senegal April 2005 One planning approach… Determine available channels from comparing Required vs Available protection ratio Eliminate other channels because of other possible interference mechanisms –Local oscillator –Image

RRC information meeting and workshop Dakar, Senegal April 2005 Conclusions Clear planning objectives National planning <> RRC planning Consideration of existing transmitting and receive facilities Use experience from the operation of analogue services Carry out tests if necessary

RRC information meeting and workshop Dakar, Senegal April 2005 Thanks for your attention