2 Which Reception Mode? Hand portable? Portable outdoor or indoor? Mobile? Fixed? HDTV ou portable?
3 Minimum required field strength Illustration of scheme of different receiving conditions for DVB-T DVB-T Transmitter Rice channel Fixed reception m Location correction factor = 9dB (C/N)f Portable reception Height loss dB m Penetration loss dB ,5m Rayleigh channel (C/N)p Mobile reception Location Correction factor = 9.1 or 13 dB ,5m m Height loss dB (C/N)m Rayleigh channel Location Correction factor = 4dB
4 Minimum required field strength Minimum median equivalent field strength for a location probability of 95% of locations +4dB for 99% of locations + 11 to 15 dB for indoor coverage
5 Illustration of services (source Jorn Andersen DK)
6 Size of service area Shape of service area Percentage of Location probability Which coverage?
7 OFDM, VSB If OFDM : 2 k, 8K System variants –Hierarchical, non-hierarchical modulation –QPSK, 16 QAM, 64 QAM –Code rate –bitrate Which DTTB Systems?
8 1.MFN : Multi Frequency Network different frequencies assigned to each site Coverage provided by a transmitter 2.SFN : Single Frequency Network The same frequency assigned to each site Synchronised Same content Self interference to be taken into account for portable and mobile (size limited) Every transmitter contribute to provide the coverage and cannot operate independently Which Network Configuration?
9 Network Configuration –MFN, SFN With technical parameters to be taken into account –Antenna height –Antenna directivity –E.r.p. –Distance between sites for MFN or SFN Re-use of existing sites; Re-use of existing sites and creation of sites Complete creation of sites For providing a service coverage Which choice of network?
10 DTTB Service Reception mode Reception Coverage (% location probability) System; 2K or 8 K, Variant Hierarchical; non-hierarchical Network configuration imply Optimisation of network choice Process for a choice of network
11 Network Configurations in Planning Configuration modes –MFN –SFN With technical parameters Antenna heights Antenna patterns E.R.P. –Distance between sites and /or –Width and shape of service area
12 Configurations modes in Planning MFN : SFN : implementation by –Few high power stations –More stations but lower radiated power –Main stations complemented by gap-filler (low power stations) Mixed MFN and SFN –In a same country some coverage are provided by MFN and by SFN –In adjacent countries, one is implementing MFN type, the other SFN type
13 MFN (and gap-filler SFN)
14 SFN synchronous signal same RF channel same content
15 Guard interval – has a major implication on the topology of SFN implementation –Duration governs the maximum echoes delay admissible by the system : maximum possible distance between co-channel transmitters More or less Large SFN SFN parameters
16 OFDM signal parameters That for non-directive antenna
17 SFN Reference structure (Open or Closed)
18 MFN Reference structure
19 Take into account requirements to describe configuration networks Use technical bases for calculation Transmitter distances between co-channel for MFN Separation distances between SFN Frequency Planning