WHAT PUSHED US INTO HTS SYSTEMS?

Transcription

1 WHAT PUSHED US INTO HTS SYSTE? Dr Hector Fenech, Director of Future Satellite Systems 16 October 2017

2 TRADITIONAL SATELLITES (KU-BAND, C-BAND) Traditional payloads are segmented into transponders Transponders include a path of equipment on the satellite that start from the uplink antenna to the downlink antenna Service areas of traditional satellites are large for a large catchment area and therefore the antenna gain is relatively low This means that the EIRP density can be maintained over a relatively small bandwidth Traditional transponders offer relatively limited capacity over relatively large areas 2

3 TRADITIONAL SATELLITES (KU-BAND, C-BAND) Capacity is a function of bandwidth and EIRP density More capacity is generated through more transponders Capped by accommodation and power constraints of each satellite More capacity is also generated through collocated satellites Capped by available spectrum Eutelsat s HOTBIRD video neighbourhood is a prime example Since a system has a single coverage over a given service area, no frequency re-use is possible These systems are ideal for broadcasting 3

4 WHAT CHANGES FOR BROADBAND Broadband connectivity calls for high capacity for individual users The equivalent of several HDTV streams may be required for a single user for a given duration Unlike linear TV, broadband connectivity is interactive User terminals have limited EIRP capability Cost of terminals is influenced by the size of the HPA The challenge is how to deliver high capacity to each user, when there are many users, using small terminals The satellite solution is High Throughput Satellites 4

5 HIGH THROUGHPUT SATELLITE HTS represents a significant opportunity to respond to the growing capacity demand for broadband applications A cost-effective solution for high demanding applications, eg broadband. HTS approach departs from the classical satellite architecture Where the service areas tend to be large catch-all coverages. HTS use a combination of spot beams and high-level frequency reuse Higher data rates at a lower cost These architectures deliver the most cost effective capacity for a given spacecraft resource. Such systems can also support double-hop meshed networks On-board processors (OBP) become necessary when latency is important but tend to be omitted to ensure the most attractive cost per capacity. 5

6 WHAT IS A HIGH THROUGHPUT SATELLITE? An HTS system is a satellite system that Splits the service area into a multi-spot architecture Exploits a high order of frequency reuse over the service area Uses the ensuing satellite antenna gain to deliver more capacity for a given satellite resource A multi-spot system enables smaller spotbeams to be used to increase satellite antenna gain To deliver a higher satellite G/T and EIRP with more bandwidth over large service areas To reduce the size of terminals 6

7 GENERAL OVERVIEW (1/2) HTS system infrastructures are bidirectional, typically with a star network topology Forward Link (outbound communications): Gateway to Users Return Link (inbound communications): Users to Gateway At the satellite antenna level, the colour scheme defines a cluster of adjacent spots where the entire spectrum on both polarisations is used θ cell A service area consisting of a number of cells covered by the same number of circular beams a) b) The typical spot size is 0.5 to 1.0 in the Ka-band Due to spacecraft accommodation constraints (~2.6m reflector aperture) Large unfurlable antennas are becoming available at 5 m resulting in spots with half of the diameter 7

8 GENERAL OVERVIEW (2/2) Capacity is the main parameter in HTS systems Due to the multi-spot coverage of an HTS system, overall capacity is dependent on bandwidth associated with each spot Optimisation of the frequency plan is one key factor for increasing overall capacity of next generation HTS systems With a direct impact on the number of gateways and consequently on system complexity and cost To satisfy the demand for increased capacity HTS solutions are evolving to higher frequencies, including Q/V band perhaps even W band for the gateway links Enables Ka-band to be maximised by users Forward link of a broadband satellite system 8

9 CAPACITY PER TRANSPONDER The same satellite hardware can be used to render more capacity In a traditional TV satellite, the capacity of transponder is say 60 Mbps In a HTS system, the same chain of satellite equipment caters of a capacity of say 2 Gbps This reduces the satellite hardware per MHz (and consequently Mbps). ACM optimises the individual user link budgets to maximise overall capacity Under static conditions for the corresponding satellite air interface Under dynamic conditions, fading etc HTS typically exploits a star network configuration where the gateway link C/N is considerably higher than that of the user link But delivers the required broadband service to small terminals. 9

10 KA-BAND FREQUENCY SPECTRUM Overall capacity is a function of the number of spots and the available spectrum to each User spot The number of spots and the associated spectrum has direct impact on number of GW s, system complexity & cost ITU ISS ISS EES ISS SR ISS Beacon ULPC HD (WRC-03) ITU REGION 1 UPLINK ees HD (WRC-03) ees ees mss HD (WRC-03) S ees S CEPT Antenna D > 4.5m ECC/DEC/(05) 01 ECC/DEC/(06) 03 (No ) Exclusively (no ) (no ) Spectrum required for future HTS applications ITU REGION 1 DOWNLINK Spectrum required for future HTS applications Spectrum required for future HTS applications Available Used by KA-SAT ITU (*) HD (*) EES sr (B) mss HD S S CEPT ECC/DEC/(05)08 ERC/DEC(00)07 ECC/DEC/ (06)03 Currently not available in all EU Countries. = Fixed Service (Terrestrial) = Fixed Satellite System (GSO or NGSO) S = Mobile Satellite System = Mobile Service R = Mobile Satellite Reserach Spectrum required for future HTS applications. Could be used on a non interfering basis with terrestrial systems (*) The use of the band GHz in R1 by in Earth-to-space direction is limited to BSS feeder links and is subject of the particular regulatory procedure of the Appendix 30A. (B) The use of GHz in Earth-to-space direction is limited to feeder links for NGSO in S ISS = Intrasatellite Satellite Service EES = Earth Exploration Satellite BS = Broadcasting Satellite HD = High Density Fixed Satellite Service SR = Space Research CAPITALS = Primary Use Lower Case = secondary Available Used by KA-SAT = Uplink (Earth-to-Space) = Downlink (Earth-to-Space) Maximising the use of Ka-band spectrum for the Users is imperative to maximise the system capacity 10 10

11 SPECTRUM CONSIDERATIONS Todays Ka-band systems share the spectrum between the users and the Gateway In some systems, it is possible not to include the gateways within the user service area This allows frequency re-use between the gateways and the users When the gateways are embedded in the user service area, the spectrum is shared Thus by definition the spectrum split is a compromise! The gateway do not need to be in Ka-band! Q/V and W band are attractive for the gateways leaving (most of the) Kaband for the terminals Propagation impairments are more significant at these bands Site diversity at system level is must to maintain the feeder link availability 11

12 Q/V-BAND FREQUENCY SPECTRUM Maximising the Ka-band spectrum for the Users implies that other spectrum is required for the GW ITU REGION 1 - UPLINK ITU S RN A AS ESS SR ESS SR ESS IS RA RNS mss SR HD HD HD CEPT EEC/DEC/(05)08 EEC/DEC/(05)08 EEC/DEC/(05)08 ITU REGION 1 - DOWNLINK ITU SR SR S ees BS BSS BS BSS BS BSS ees ees ees S SR ms ms ms HD (WRC 2000) HD HD (WRC-2000) CEPT ECC/DEC/(02)04 = Fixed Service (Terrestrial) BS = Broadcasting Service RN = Radio Navigation = Uplink (Earth-to-Space) = Fixed Satellite System (GSO or NGSO) = Mobile Service S = Mobile Satellite Service R = Mobile Satellite Service BSS = Broadcasting Satellite Service HD = High Density Fixed Satellite Service RA = Radio Astronomy A = Amateur AS = Amateur Satellite RNS = Radio Navigation Satellite SR = Space Research IS = Intersatellite EES = Earth Esploration Satellite = Downlink (Earth-to-Space) GW s operated in Q/V-band allows maximisation of: User spectrum - with a consequential increase in system capacity GW spectrum - with a minimisation of the number of GW s and associated cost 12

13 W-BAND FREQUENCY SPECTRUM GWs operated in W-band allows maximisation of: User spectrum - with a consequential increase in system capacity GW spectrum - with a minimisation of the number of GW s & associated cost 13

14 WHAT PUSHED US INTO HTS SYSTE? The quest for broadband access on a more ubiquitous level For land applications for the unserved and the underserved residential user For maritime and aeronautical applications where terrestrial services may be limited The quest for satellite services at costs comparable to terrestrial services More efficient satellite resource utilisation More efficient ground segment 14

15 Thanks for your attention 15