ESA Ground Segment Technology Workshop 5-June-08 Ka band for Broadband and IPTV
2 Broadband Requirements
BB Current challenges 3 Although there is a clear BB gap where the satellite is welcome, many barriers are slowing down the penetration: Capacity cost: xdsl typically provides 10x the volume the satellite can deliver for the same price, more to come in the future DVB-S2 improved the case, but it s not enough Terminal cost: a reduction of 10x has been achieved but it s still much more than terrestrial technologies Installation complexity: DiY is now implemented for antenna pointing assistance but preliminary steps are still a barrier (hole in the wall, antenna fixation, cable installation ) GEO delay: PEP and prefetching are good mitigations but it will never be the xdsl experience Satellite cannot be more than a gap filler for BB, it should thus only target the gap, providing good enough end-user experience while mitigating the capacity consumption
Satellite Capacity Cost At all frequencies (Ku and Ka), reducing the satellite footprint allows to lower the capacity cost. Commercial and coordination constraints in Ku limit however the possibilities. The capacity cost can be reduced by changing from Continental coverage to Local / Linguistic coverage. For a given TWT, if the surface covered is divided by 4, the power received by a given antenna is multiplied by 4. A straightforward way to reduce the capacity cost is to widen the transponder bandwidth accordingly, multiplying the capacity per TWT by 4. In a multi-beam approach, the same frequency can be reused in non-adjacent beams to enhance the overall satellite capacity. The usage of wideband transponders (operated in single carrier) however impose technological changes. 4
Ka Band for Broadband - Motivation 5 More freedom to reduce the beam size in Ka than in Ku Reduced beam size improves the cost structure for BB: FWD : Higher EIRP Higher Bit Rate per TWT Typical improvement : x 4 (European National Beams) x 10 (Small Regional Beams) Reduced beam size improves the system performances RTN : Higher G/T Higher Bit Rate per terminal The rain fade impact is marginal thanks to ACM 90% of the time can be considered as clear sky The antenna size should be kept as large as possible The antenna size impacts directly the capacity cost Selection : maximum commercially acceptable
DVB-S2 with Time Slicing for high speed TP SLC1 SLC2 SLCN SLC1 SLC2 SLCN The traffic is divided in N slices The traffic to a given terminal is only in one slice at a given point in time Terminals only decode 1 slice over N to keep a minimum complexity Possible example of parameters Symbol Rate : 200 Msps Bit Rate : 500..800 Mbps (ACM/VCM dependant) Number of slices : 8 Decoded bit rate per terminal : < 100 Mbps Statistical multiplexing domain = Slice ACM/VCM domain = Slice The corresponding signaling is not standardized (minor issue : a slice can be considered as a virtual transponder) 6
Adaptive Coding and Modulation CNR Variation at 20 GHz 7 [ db] [ db] Split Betzdorf Madrid 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Percentage of time [%] CNR Variation at 12 GHz Kinshassa Betzdorf Madrid 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Percentage of time [%] ACM brings a significant bit rate benefit: No ACM : bit rate limited by the worst case link budget ACM : bit rate optimized for the actual link budget Link budget variations are due to EIRP variation in the footprint Pointing accuracy Rain fade Absence or presence of interferences ACM is mandatory for Ka band in all the regions and for Ku band in heavy rain zones (Africa ).
8 (IP)TV Requirements
Ka Band for TV - Motivation Ka allows smaller antenna size for a given satellite spacing 30 cm in Ka is equivalent to 50 cm in Ku Ka band is now quasi mass-market Thanks to Direct TV Sensitivity to rain fade can be compensated National coverage instead of pan-european VCM + Scalable Video Should be used to trigger a new market segment New targets thanks to micro-antennas New generation receivers (DVB-S2 VCM, Scalable Video ) Key for future growth 9
Clear Sky HDTV CNR Variation at 20 GHz [db] 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Percentage of time [%] QPSK 1/2 8PSK 2/3 QPSK 1/2 8PSK 2/3 SD ΔHD Split Betzdorf Madrid In a classical approach all terminals are penalized by the worst case link budget of the worst case terminal. This penalty is extreme in Ka Combination of VCM and scalable video minimize this penalty: Scalable video (Hierarchical source coding): HD @ 8 Mbps SD @ 2 Mbps + ΔHD @ 6 Mbps For 99% of the time of the worst case terminal, SD and ΔHD are available For 99.9 % of the time of the worst case terminal, SD is available Efficiency close to the 8PSK 2/3 one 10
New Ka DTH Terminal possible definition Services: IPTV only (in Ka) Frequency: Ka band Antenna size: 20..30 cm With interference suppression Up-to-date technologies : DVB-S2 VCM, scalable Video Clear Sky HDTV : HDTV most of the time, SDTV during rain fade DVB-S2 VCM : Robust SD + Clear Sky HD Complement LAN interface directly on the other side of the wall Wi-Fi, PLC No coaxial cable to pull 11
Ku/Ka DTH Terminal Services: IPTV (in Ka) and TS-TV (in Ku) Frequencies: Ku and Ka band Single feed (new dual frequency LNBs) Dual feed (using regular Ku and Ka LNBs) Antenna size : 50..60 cm Allow full access to new services in Ka: Clear Sky HDTV in Ka remains available during rain fade due to larger antenna size 12
Triple Play Terminal Definition Services: BB (in Ka), Voice (in Ka), IPTV (in Ka) and TS-TV (in Ku) Frequencies: BB Forward Link : Ka BB Return Link : Ka TV: Ku and Ka Configurations: Multiple feeds for compatibility with existing LNBs Single feed with multiple frequencies Antenna Size: 60..80 cm for minimum BB service price 13
14 Technological Development Required
Technological development required (if justified by quantities) Low cost broadband up-to-date modems able to feed domestic LANs with triple play services. Mass-market satellite routers able to feed domestic LANs with TV services Scalable Video decoders (based on H264) Mass-market DVB-S2 chips supporting VCM for TV and ACM for BB Very high symbol rates (possibly in time-slicing mode) RF components allowing to further reduce the cost of the BB modems LNBs with interference suppression Multi-frequency LNBs: Ku RX / Ka RX Multi-frequency ilnbs: Ku RX / Ka RX / Ka TX 15
16 Conclusion
Conclusion The BB capacity cost can be reduced with multi-beam satellites for which Ka band is well suited Ka Band enables a new TV market segment using ultra small antennas Ka Band combined with VCM and scalable video allows low cost Clear Sky HDTV : HDTV 99% of the time, degrading to SDTV during the rain fade (less than 1% of the time) Usage of Ka in complement to Ku satellite would allow market segmentation via the antenna size: 20..30 cm Ka antennas for new TV customers 40..60 cm Ka/Ku antennas for existing TV customers 60..80 cm Ka/Ka/Ku antennas for triple play customers 17