Evolution of Front Ends for Satellite Communications in Ka- band J. Fikart IEEE ComSoc Presentation 10 Jan 2005 Evolution of Front Ends: Outline Part 1: Satellite Communications: Why Ka- band? Part 2: “Generic” Satcom Systems with Fixed Terminals Part 3: Front End for ASTRA SITs Part 4: Ka-band Portable Terminal Part 5: Ka-band Challenges and Trends 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Part 1: Satellite Communications: Why Ka- band? IEEE ComSoc Presentation 10 Jan 2005 Outline 1. Satellite bands for DTH TV, VSATs 2. Ka-Band Pros and Cons 3. Historical Overview X The beginnings X First Satellites X “Newer” Satellites X Local contribution 4. New Ka-Band Satellite Systems ¾ Recent Ka-Band Satellite Launches 5. Conclusions 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Satellite bands for DTH TV, VSATs Ka, Ku- and C- bands : X C: Rx = 3.7 – 4.2 GHz Tx = 5.925 – 6.425 GHz X Ku: Rx = 10.75 – 12.75 GHz with sub-bands Tx = 14.0 – 14.5 GHz (extended to 13.75 GHz) X Ka: Rx = 19.2-20.2 GHz Eu & US 20.405 –21.105 GHz Asia (Korea) Tx = 29-30 GHz Eu & US 30.135 - 30.835 GHz Asia (Korea) Most often used Ka Rx/Tx = 19.7-20.2/29.5-30 GHz 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Ka-Band Pros and Cons X Larger effective bandwidth Higher frequency = smaller wavelength = smaller satellite footprint = many spot beams = frequency re-use Example: Typical 500 MHz allocation in a satellite payload is effectively multiplied 4 -10 times through polarization and frequency reuse using spot beam geographical coverage. X Higher satellite EIRP for same power, antenna size X Smaller ground terminal VSAT antenna diameters X Reduced interference, fewer regulatory restrictions. X New satellites, some with OBP 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Pros and Cons: narrow beams P = Power received R Earth PT = Power transmitted PR GTxA = Gain of Tx antenna Rx Ku R = distance (sat. to earth) f(Ku)=11 GHz Ka A A = area of Rx antenna RxA RxA f(Ka)=19 GHz GTxA PT R Rx power in Ka ≈ 3 x Rx power in Ku SAT Tx 1 π 2 DDf2 π 2 2 2 PPG===A and G η AAη R T TxA4πR 2 RxA TxA λ2 c2 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Pros and Cons: Polarization E CAL I RT E V RHCP ANT ANT HORI- LHCP E ZONTAL ANT Linear ANT Circular 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Pros and Cons: Spot beams (e.g.- US) Example: 2 frequency bands and 2 polarizations 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Pros and Cons: Effects of weather Main propagation and antenna effects: XPath loss due to rain and cloud attenuation Depends on location:more loss in heavy rain regions vs. “misty” rain locations. Also, loss increases with frequency (Ka 5 dB > Ku!). XDe-polarization due to ice crystals in clouds hence cross-polarization interference. XAntenna wetting, particularly wet feed. This must be taken into account in overall system design (larger antennas, Tx power). 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Pros and Cons:Rain fade countermeasures The following mitigating techniques can be used: X Site diversity for gateways X On-board ALC for forward link X Higher satellite EIRP for forward link X Uplink Power Control in terminals & gateways X Larger user antennas for critical applications X Advanced modems with variable bit rate and code rate (slow down during fade!) X Antennas less susceptible to wetting loss This, combined with Ka-band advantages and less stringent availability requirements, enables the use of Ka-band for satellite communications. 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Historical Overview: The beginnings Demand for wide-band services started to be evident in the late 1970’s NASA, NASDA (Japan), ESA and ASI Space Agencies started to pioneer Ka-band Wide total bandwidth but slow going initially due to: X large rain attenuation X Cost of providing high-availability commercial services Then emphasis changed to Direct-to-User (DTU) services with less stringent availability requirements Ä Era of broadband satellite communications capable of linking users around the world has opened 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Historical Overview: First Ka Satellites The following were the first satellites, used mostly for experimental purposes (propagation, earth station hardware, various types of traffic etc.) X ETS-II: Japan, 1977 X Olympus: Europe (ESA), 1989 X Kopernikus: Germany, 1990 The above were “bent-pipe” types. The next two below had OBP (On-Board Processing): X Italsat: Italy (ASI), 1991 X ACTS: USA (NASA), 1993 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Historical Overview: “Newer” Ka Satellites By 2001, several “commercial” satellites with a Ka- Band payload were (and are still now) in service: Italsat F2 has been used in trials involving a university network as well as some telephony backhaul services within the European continent. KoreaSat 3 has been used for a Distance – Education network. Astra’s 1H satellite has been used as part of the AstraNet Return Channel System (ARCS) later re-named BroadBand Initiative (BBI) for Multimedia applications. 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Historical Overview: Local Projects (MPR Teltech, IMT ComSys, NORSAT) X Picoterminal (MPR, 1993 – 1996, with ESA): First Ka-band (30/20 GHz) briefcase terminal X VSAT terminal (IMT, 1995-1998, with ESA): 30/20 GHz, up to 2Mb/s, 1.5m antenna X SIT (Satellite Interactive Terminal) ODUs (NORSAT, 1998- 2002) for ASTRA’s BBI for Multimedia: 30/12 GHz, 128-2000 kb/s,75-120 cm X Trial ODU for the IMMIS system (1998- 2002) NORSAT partnered up with Alenia Spazio. X ODUs for Korea Telecom Distance education network: 30/20 GHz, up to 2Mb/s,120 cm ant. 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 New Ka-Band Satellite Systems/Projects As of 2001, there were many industry announcements for new satellites that would include Ka-Band communications payloads and these were expected to be launched in the period of early 2002 to end of 2004. X Of these, there were several satellites already under construction that could be considered probable to succeed. 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Ka-Band Satellite Launches Plans: 2001 WildBlue 1 Launch 109.2 or 118.7° WL North America GE Star 1&2, NIMIQ 2 Launch 91° WL Telstar 8 ASTRA 1K Launch 19.2 ° EL North America Europe TELEDESIC Launch (LEO x 288) SpaceWay Global Launch 99 and 101 ° WL ANIK F2 Launch 111.1° WL Assessment North America date Today Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 2001 2002 2003 2004 Echostar 9 Launch IPSTAR Launch EuroSkyWay Launch 16.4° EL 121° WL 120° EL Europe North America N&S Asia Planned Ka-Band Satelltie ITALSAT F2 16.4° EL HOTBIRD 6 Launch 13° EL Eutelsat W3A Launch 7° EL Launch Schedule Window Europe Europe Europe ASTRA 1H 19.2° EL In Service Europe KOREASAT 3 113° EL NSS 6 Launch 95° EL Highly Probable Europe N&S Asia Probability Unkown 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Ka-Band Satellite Launches: 2004 WildBlue 1 Launch 109.2 or 118.7° WL North America GE Star 1&2, NIMIQ 2 Launch 91° WL Telstar 8 ASTRA 1K Launch 19.2 ° EL North America Europe TELEDESIC Launch (LEO x 288) SpaceWay Global Launch 99 and 101 ° WL ANIK F2 Launch 111.1° WL North America Q2 Today X Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 05 2001 2002 2003 2004 Q1 Echostar 9 Launch IPSTAR Launch EuroSkyWay Launch 16.4° EL 121° WL 120° EL Europe North America N&S Asia Planned Ka-Band Satelltie ITALSAT F2 16.4° EL HOTBIRD 6 Launch 13° EL Eutelsat W3A Launch 7° EL Launch Schedule Window Europe Europe Europe ASTRA 1H 19.2° EL In Service Europe KOREASAT 3 113° EL NSS 6 Launch 95° EL Highly Probable Europe N&S Asia Probability Unkown 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Conclusions X Ka-band systems could provide up to 10 Gb/s throughput compared to 1Gb/s in Ku-band X Speeds of 10 Mb/s up, 100 Mb/s down possible X OBP in satellites will enable mesh connectivity X Less interference & fewer regulatory problems X Rain fades require more margin in link budgets ≈ 5 dB more than in Ku-band for 99% availability Mitigation techniques such as higher satellite EIRP, uplink power control and variable bit rate modems in terminals may have to be used Pay attention to antenna wetting (keep feed dry) X Smaller antennas ¨ smaller portables 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Conclusions In Ka-band, this is possible! 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Part 2: “Generic” Satcom Systems with fixed terminals 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 Outline General overview Network Configuration Earth station subsystems:ODU, IDU, IFL Description of ODU components • Complete ODU • Antennas, feeds, OMT/diplexers • Transceivers Specific example Korea Telecom Project (KoreaSat III) 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 General: Satellite Network Configuration Ka Band/Ku Band Payload 30 GHz R et ur n C ha R nn e el External Networks tu rn C h an u n R K d e u e n l K d t a z n u User Terminal a r B HB n B V 2 d C D G te G h E s a a Service/Content n c l z 0 n MP d aH Provider e a n 3 z l o igG r S Ku Band H B 0 Tx Front-End 2 G 0 User Terminal 2 Ka Band User Terminal HUB Ka Band Rx Front-End Star Network Example 1/10/2005 IEEE ComSoc Presentation 10 Jan 2005 General: Earth Station & its Subsystems Audio Fig.