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Multi-GNSS Future:
GPS, GLONASS, Galileo, BeiDou, …
Pratap Misra
Sogei Workshop GNSS Technology Advances in a Multi-Constellation Framework
Rome, April 22-23, 2013
Source: International Committee on GNSS (ICG)
© 2013 Pratap Misra
GNSS Global Satellite Navigation System
• Originally defined by the International Civil Aviation Organization (ICAO) as: “a worldwide position and time determination system
that includes one or more satellite constellations, aircraft receivers and system integrity monitoring, augmented as necessary to support the required navigation performance for the intended operation”
• GNSS = a satellite navigation system • All GNSSs follow the GPS model
2
© 2013 Pratap Misra
Multi-GNSS Future* Outline
• Why Do We Need So Many Systems? • GNSSs Under Development:
– Global Systems: GPS III, GLONASS, Galileo, & BeiDou
– Regional Systems: Japan’s QZSS, India’s IRNSS
– Regional Augmentations: US’ WAAS, NDGPS; Europe’s EGNOS; Japan’s MSAS; Russia’s SDCM; India’s GAGAN
• Coexistence: Compatibility • Cooperation: Interoperability • Competition: Who will be Number 1?
3 * Opinions of the author alone
© 2013 Pratap Misra
GNSS Status • 75 working satellites in early 2013
– GPS: 31 – GLONASS: 24 – Galileo: 4 – BeiDou: 16
• 5-7 Launches Scheduled in 2013: 2 GPS IIFs; 2 Galileo; 1 GLONASS-K
• Only GPS is operational and in > 1 billion mobile devices – market expected to grow to 5 billion
• 4 operational systems with 120 satellites in 2020
4
Source: ICG-7 presentation by Dr. Lu Xiaochun
© 2013 Pratap Misra
It’s Not Just About Navigation, It’s About Economics & Politics
• Sovereignty • National Pride • Markets & International Trade
– Brand Building, Consumer Confidence • Standards & Certification • Intellectual Property & Patents • Military Use & National Security
5
Source: ICG
GNSS Users’ Perspective
6 Source: GPS SPS PS, 2008
© 2013 Pratap Misra
Performance Metrics My System is Better than Yours
• Accuracy • Availability of Service • Integrity (or Reliability)
– Can I count on my position estimate to be ‘correct’? • Robustness
– Can the system withstand ‘small’ disturbances? • Security • Challenge:
– Deliver service like a utility: water or power supply – Rigorous, constant maintenance: No screw ups!
7
© 2013 Pratap Misra
GPS has Set High Standards
• Delivers a lot more than promised – Near flawless performance over 20 years
• Made it Look Easy • A Victim of its Own Success?
– Satellites last for ever, no screw-ups – No urgency in Washington re budgets?
• Success Breeds Imitators • Can GPS Remain #1 ?
– Remains to be seen: The race is GPS’ to lose – Not sitting still
8
© 2013 Pratap Misra
9
GPS Modernization
• Space Segment – Cross links among satellites, flexible power, spot beam,
integrity monitoring – Additional, more capable military signals: M-code on L1
and L2 – Additional, more capable civil signals: L2C, L5, L1C
• Control Segment – Block II OCS OCX to fly new spacecraft – Distributed architecture, security
• User Segment – MGUE (Mil. GPS User Equip’t): Enhanced A-J, A-S, A-T – New security architecture: SAASM Pronav – New paradigm: from ‘form-fit’ military receivers to GPS
chipsets
GPS III satellite Source: Lockheed
10
GPS Signal Modernization
C/A Code • Civil Use • Degraded
P(Y) Code • Encrypted
P(Y) Code • Encrypted
1227.6 MHz (L2)
1575.42 MHz (L1)
(2 May 2000)
M-Code (Starting 2005)
M-Code (Starting 2005)
Misra 2010
Civil Signal (Starting 2010)
L2C-Code (Starting 2005)
1176.45 MHz (L5)
L1C (2014)
Direct Sequence Spread Spectrum
11
×
×
=
carrier
spread spectrum waveform
Tc
Td data waveform
modulated spread spectrum signal
T0
f0 = 1/T0 = carrier frequency (Hz) Rc = 1/Tc = chipping rate (chips/s) Rd = 1/Td = data rate (bits/s)
Source: Dr. Chris Hegarty, MITRE
Binary Offset Carrier Modulation
×
×
=
×
Carrier
Spreading code
Square wave
Data
BOC signal*
*Shown at baseband (i.e., without carrier)
Tsq
Fsq = 1/Tsq = subcarrier frequency (Hz)
12
Source: Dr. Chris Hegarty, MITRE
13
Evolution of GPS Signals
1176.45 MHz
Block II / IIA / IIR 1989 - 2005
Block IIR-M Starting in 2005
Block IIF Starting in 2010
1227.6 MHz 1575.42 MHz
C/A
P(Y)
M L2C M
P(Y)
L1 L2 L5
14
> $1b award to LMC in 2008
> $1b award to Raytheon in 2009
15
© 2013 Pratap Misra
16
Global’naya Navigatsionnaya Sputnikovaya Sistema
GLONASS • History
– Developed by Soviet Union, first launch: 1982 – Declined under Russia, but now revived – Have launched 81 satellites so far
• Constellation – 24 satellites in 3 orbital planes, 64.8º inclination – 19,100 km altitude, 11 ¼ hour period
• Signals – 3 allocated bands: G1 (1602 MHz), G2: (1245
MHz), G3 (1202 MHz) – C/A-like code: 511 chips, 1 ms code period, 50
bps data – All SVs use same PRN with frequency division
multiple access (FDMA) using 16 frequency channels, reused for antipodal SVs
GLONASS Constellation Source: ROSCOSMOS
17
Soviet-built GLONASS Aviation Receiver & Tool box (circa 1990)
ASN-16
© 2013 Pratap Misra
GLONASS Status & Plans
• 24 working satellites in 2013 • New satellites GLONASS-K and
GLONASS–K2 under development • CDMA signal planned • No significant user base
18
GLONASS-M
GLONASS-K
Source: ROSCOSMOS
19
Galileo • Jointly financed by EC and ESA • “Seen” as a civil system, but
military role may emerge • 5 Services being considered
– Free: Open Service – For a Fee :
• Commercial Service • Safety-of-Life Service • Public Regulated Service • Search & Rescue Service
• 30 MEOs in 3 planes inclined at
56° • First experimental satellite
launched in 2005
Source: ESA
© 2013 Pratap Misra
Galileo Status & Plans
• 4 in-orbit validation (IOV) satellites (launched in 2011 & 2012)
• Ground infrastructure (monitor stations & control centers) capable of generating navigation messages
• First 3-D positioning demonstrated at ESTEC (March 12, 2013)
• Plans – First full-operational capability (FOC)
satellites to be launched in 2013 – 18 FOCs in orbit in 2014
• Budget of €7.9 billion for deployment & exploitation (2014-2020) under discussion
20
Source: ESA
© 2013 Pratap Misra
21
Etymology of BeiDou
• BeiDou (北斗)* – Bei: North/Northern
– Dou: a traditional Chinese container used for measuring grain by volume
– BeiDou: Big Dipper constellation • Ladle • Butcher’s cleaver • Drinking gourd • Coffin & mourners • Charles’ wain
*Courtesy of Dr. Grace Gao, Stanford University
Source: Wikimedia
© 2013 Pratap Misra
22
BeiDou/Compass
• Chinese • Beidou -- 1
– Regional system – 3 GEOs orbited in 2000 – 2003 – ‘Active’ system
• Beidou-- 2 or Compass – Global system (under
development) – Plan: 5 GEOs, 27 MEOs, 5
IGSOs
© 2013 Pratap Misra
BeiDou Status & Plans
• Constellation: 5 GEOs, 5 IGSOs, 4 MEOs • Regional (Asia/Pacific) system operational • Launched 16 BeiDou-2 satellites since 2007,
No launches in 2013 • Released an ICD for B1 open service SIS in
2012 • Plans:
– Final constellation: 5 GEOs, 3 IGSOs, 27 MEOs
– 40 more satellites to be launched – Operational:2020
23
© 2013 Pratap Misra
Marketing a GNSS: You’d Like Our System Better!
– Protecting Domestic Markets, Finding Foreign Markets
– Balance between open trade and Protectionism
– Regulation (A Little Arm Twisting) • Russia’s plan to “require” GLONASS in civil aircraft operating in
its airspace; import tariffs on GNSS receivers that don’t include GLONASS
• China’s plan to “require” transportation operators to use BeiDou
– Political Muscle • Russia agreement with India to promote GLONASS adoption
24
Marketing GPS-3 Is This the Best of Madison Avenue?
27
Case for QZSS-1
31 Source: A presentation by Japan at the ION GNSS 2008 in Savannah, Georgia, on 17 September 2008
Case for QZSS-2
32 Source: A presentation by Japan at the ION GNSS 2008 in Savannah, Georgia, on 17 September 2008
© 2013 Pratap Misra
QZSS Status
• 3 satellites planned in highly elliptical 36,000-km altitude orbits
• First satellite launched in 2010
33 Source: JAXA
© 2013 Pratap Misra
IRNSS Indian Regional Navigation Satellite System
• 3 GEOs, 4 IGSOs • First launch: any day
34
Source: ISRO
© 2013 Pratap Misra
Multi-GNSS Future* Outline
• Why Do We Need So Many Systems? • GNSSs Under Development:
– Global Systems: GPS III, GLONASS, Galileo, & BeiDou
– Regional Systems: Japan’s QZSS, India’s IRNSS
– Regional Augmentations: US’ WAAS, NDGPS; Europe’s EGNOS; Japan’s MSAS; Russia’s SDCM; India’s GAGAN
• Coexistence: Compatibility • Cooperation: Interoperability • Competition: Who will be Number 1?
35 * Opinions of the author alone
© 2013 Pratap Misra
Coexistence & Cooperation among GNSSs
36
• Coexistence: Compatibility Living peacefully with others despite fundamental
disagreements
• Cooperation: Interoperability Working together for a common purpose
Coexistence: RF Compatibility Spectrum Allocations
37
GPS GLONSS GPS
L2 L1
1240 1216 1563 ~ ~ 1587 MHz
L-Band: 1 GHz – 2 GHz
LF MF HF VHF UHF SHF
30 kHz 300 kHz 3 MHz 30 MHz 300 MHz
3 GHz
GPS
Radio Spectrum
Coexistence: RF Compatibility Spectrum Allocations
38
Galileo GPS
L5, E5A
Galileo GPS GLONASS Galileo Galileo GPS
E5B L2 G2 E6 E2 L1 E1
1164 1188
1215
1240 1256
1260
1300
1559
1216 1563
~ ~
G1
1593
GLONASS
1610
1587 MHz
L-Band: 1 GHz – 2 GHz
LF MF HF VHF UHF SHF
30 kHz 300 kHz 3 MHz 30 MHz 300 MHz
3 GHz
GNSS
Radio Spectrum
Coexistence: RF Compatibility GPS, GLONASS, & Galileo Fill Upper L-Band
39
Source: ?
GNSS Signal Plans
40
Future CDMA signal
SBAS (US Europe
India Japan)
QZSS (Japan)
IRNSS (India)
COMPASS (China)
Galileo (Europe)
GLONASS (Russia)
GPS (US)
L1 L5 L2
Compass & IRNSS In S-band
1560 1570 1580 1590 1600 16101170 1180 1190 1200 1210 1220 1230 1240 1250 1260 1270 1280 1290 1300 Frequency (MHz)
Source: Dr. John Betz, MITRE
© 2013 Pratap Misra
Coexistence: Political Compatibility
• Galileo’s erstwhile plans to broadcast over the M-code frequencies
• BeiDou’s current plans to broadcast over Galileo’s PRS code
41
© 2013 Pratap Misra
Cooperation: Interoperability The More Systems, The Better
• Common time standard: UTC – Each GNSS uses its national time standard – Transmit biases among national standards
• Common coordinate frame: ITRF – Each GNSS uses its reference coordinate frame – Establish transformations among coordinate frames
42
GPS + GLONASS + Galileo in 2013
43 Source: Curran-Petovello-Lachapelle, GPS World, April 2013
U.N. is on the Job
44
http://unoosa.org/oosa/en/SAP/gnss/icg.html
45
© 2013 Pratap Misra
GPS III • Next generation satellites
– First launch anticipated ~2014
• Potential Block III features (to be phased in incrementally): – New L1 civil (L1C) signal – Increased levels of accuracy, availability, reliability, and integrity – High-speed uplink/downlinks/cross-links – “Spot beam” for military M-code signal
• Longer pseudorandom codes for open signals – Improves cross-correlation performance
• Data-less (pilot) components – Portion of signal energy devoted to component with no navigation
data modulation – Enables more robust tracking
• Advanced modulation schemes – Binary offset carrier and variants
• Robust forward error correction – Convolution encoding, low-density parity check
• More precise navigation data
46
Hegarty
© 2013 Pratap Misra
Spectrum Sharing Considerations
• All systems recognize the need for Radio Frequency Compatibility – Technical details for assessment and acceptance still being worked
• Increasing recognition of National Security Compatibility for military or authorized signals – Pioneered by GPS for M code signal – Mimicked by Galileo for PRS – Accepted by IRNSS – Still being discussed with GLONASS and COMPASS
• Interoperability of civil signals with GPS civil signals viewed as benefitting everyone – New systems become useful even with only a few satellites launched – GPS remains the world standard as others mimic it – Users obtain better geometry and availability from more satellites
47
© 2013 Pratap Misra
QZSS Status
• 3 satellites planned in highly elliptical 36,000-km altitude orbits
• First satellite launched in 2010
48 Source: JAXA
© 2013 Pratap Misra
IRNSS Indian Regional Navigation Satellite System
• 3 GEOs, 4 IGSOs • First launch: any day
49
Source: ISRO
50
GPS III Source: Lockheed-Martin.
51
© 2013 Pratap Misra
GPS Modernization
• First announced in 1998 by Vice President Gore – Additional civil signals
• More – and More Capable – Signals – Civil signals: from 1 to 4 – Military signals: from 2 to 4
• “Classic” GPS Modernized GPS GPS III • 2005 was the Year of Transition
– First GPS Block IIR-M satellite launched – An additional civil signal: L2C – Additional military signals on L1 and L2: M-codes
• GPS III to be completed ~ 2020
52
© 2013 Pratap Misra
53
GPS Modernization
• Space Segment – Cross links among satellites, flexible power, spot beam,
integrity monitoring – Additional, more capable military signals: M-code on L1
and L2 – Additional, more capable civil signals: L2C, L5, L1C
• Control Segment – Block II OCS OCX to fly new spacecraft – Distributed architecture, security
• User Segment – MGUE (Mil. GPS User Equip’t): Enhanced A-J, A-S, A-T – New security architecture: SAASM Pronav – New paradigm: from ‘form-fit’ military receivers to GPS
chipsets
The current Hand-Held Military Receiver Suffers in Comparison to Civil
Counterpart
54
• Comm: voice, email/text message • Positioning: GPS, Wi-Fi, cell towers • Camera: geo-tagged pictures • Social networking: Where other iPhones are • … • Lost iPhone
DAGR
Hand-Held Military Receiver Suffers in Comparison to Civil Counterpart
55
DAGR
Common GPS Module (CGM)
Enablers Build “Engines” + =
Integrators Build Applications
Global GPS Use
Commercial Method (GPS “engines” enable multiple applications)
Proposed MGUE Approach (Emulate commercial, Build the engine!)
GPSW Builds Enabling “Engines” + =
Integrators Build Applications
Global Military GPS Use
Common GPS Module (CGM)
GPS Has Raised Expectations
57
Instantaneous, meter-level position estimates EVERYWHERE Performance metrics: accuracy, continuity, integrity, availability Intense research focus on multi-sensor navigation
© 2013 Pratap Misra
Current Navigation Challenges Multi-Sensor Navigation
• Open interface standards for plug-and-play sensors • Software architectures to accommodate re-configuration of
sensors • Dynamic calibration/characterization of sensors of diverse
quality • Kalman-type filters to process asynchronous data from
changing sensors of diverse quality New Technologies
• Better MEMs sensors, Atomic reference mass accelerometers & gyros (“cold atoms interferometry”)
• Chip-scale atomic clocks (CSACs) • Inertia of elastic waves/self-calibration/3-D fabrication
58
Ohio State Univ. photo
59
© 2013 Pratap Misra
60
BeiDou/Compass
• Chinese • Active system
– 2 - 3 geostationary satellites orbited in 2000 – 2003
– I MEO launched in 2007 • Mission: unclear • (08/15/2011) four geostationary
satellites, a medium earth orbiting spacecraft, and the four IGSO satellites now on orbit.
© 2013 Pratap Misra
61
Implications of Foreign GNSSs for GPS
• Technical – Compatibility and Interoperability
• Political – Sovereignty, national pride, – Who is #1?
• Economic – Commercial activity, technical innovation
• Military – Complicates Navwar issues:
• Protect U.S. military use • Prevent hostile use, • Preserve civil use (outside the area of military ops)
© 2013 Pratap Misra
62
Satellite Navigation Overview Outline
• Principles of Satellite Navigation
• GPS Overview: System, Signals and measurements, Performance
• Applications and Performance Metrics • Potential Partners/Rivals: GLONASS,
Galileo, BeiDou/Compass, …
Frequency Plans
Frequency Plans*
*Adapted from T. Grelier et al., Inside GNSS, May/June 2007
Frequency Plans*
*Adapted from T. Grelier et al., Inside GNSS, May/June 2007 65
© 2013 Pratap Misra
66
GLONASS • History
– Developed by Soviet Union, first launch: 1982 – Declined under Russia, but newly revived – Similar to GPS: Passive, one-way ranging – 10-12 working satellites over the past 5 of years, currently 16 – No significant user base
• Constellation – 24 satellites in 3 orbital planes, 64.8º inclination – 19,100 km altitude, 11 ¼ hour period
• Signals – 3 allocated bands: G1 (1602 MHz), G2: (1245 MHz), G3 (?) – C/A-like code: 511 chips, 1 ms code period, 50 bps data – All SVs use same PRN with frequency division multiple access
(FDMA) using 16 frequency channels, reused for antipodal SVs • Plans: 18 SVs in 2008, full constellation in 2011 (?)
67
GPS+GLONASS Satellite Visibility
Misra/1997
HDOP VDOP
2 3 4 5 6
Dilution of Precision (DOP) 1 0
99.999 99.99
99
95 90
50
30
10
1
0.1
0.01
GLONASS-21 GPS+GLONASS (2x21)
10 9 8 7
GLONASS-21 GPS+GLONASS (2x21)
Prob
abili
ty (%
)
Prob
abili
ty (%
)
50 30
10
1
99.9
70
4 6 8 10 12
Satellites Visible 2 20 18 16 14
68
GPS & GLONASS Position Estimates* 1-Minute Samples, 15 June 1996
69
GPS & GLONASS Position Estimates* 1-Minute Samples, 15 June 1996
© 2013 Pratap Misra
70
BeiDou/Compass
• Chinese • BeiDou: Regional System
– Active system – 2 - 3 geostationary satellites
orbited in 2000 – 2003 • Compass: GNSS
– 1 MEO launched in 2007 •
© 2013 Pratap Misra
71
Summary: Take-Away Points • Satellite navigation systems exploit basic properties of radio waves:
Transit exploited the Doppler effect, GPS exploits the known speed of propagation
• GPS is based on the old idea of trilateration, but implemented with the technology of the second-half of the 20th century: space-based radio transmitters, ultra-stable clocks, and spread spectrum signals
• A GPS receiver measures pseudoranges to the satellites by measuring pseudo-transit times of radio signals. It takes 4 satellites (i.e., 4 pseudoranges) in order to estimate position (x, y, z) and time t
• With a clear view of the sky, it’s easy to get positioning accuracy of several meters with a $100 GPS receiver, or relative positioning accuracy of millimeters with a pair of $1000 receivers.
• GPS satellites are 20-watt transmitters 20,000 km away, so the signals reaching the earth are very weak and, therefore susceptible to interference.
• The success and breadth of GPS applications is attributable largely to “the chip.” The VLSI revolution was well-timed for GPS
© 2013 Pratap Misra
GPS Modernization
• First announced in 1998 by Vice President Gore – Additional civil signals
• More – and More Capable – Signals – Civil signals: from 1 to 4 – Military signals: from 2 to 4
• “Classic” GPS Modernized GPS GPS III • 2005 was the Year of Transition
– First GPS Block IIR-M satellite launched – An additional civil signal: L2C – Additional military signals on L1 and L2: M-codes
• GPS III to be completed ~ 2020
72
73
GPS Signal Modernization
C/A Code • Civil Use • Degraded
P(Y) Code • Encrypted
P(Y) Code • Encrypted
1227.6 MHz (L2)
1575.42 MHz (L1)
(2 May 2000)
M-Code (Starting 2005)
M-Code (Starting 2005)
Misra 2010
Civil Signal (Starting 2010)
L2C-Code (Starting 2005)
1176.45 MHz (L5)
L1C (2014)
© 2013 Pratap Misra
74
Galileo GPS
L5, E5A
Galileo GPS GLONASS Galileo Galileo GPS
E5B L2 G2 E6 E2 L1 E1
1164 1188
1215
1240 1256
1260
1300
1559
1216 1563 ~ ~
G1
1593
GLONASS
1610
1587
© 2013 Pratap Misra
75
GLONASS • History
– Developed by Soviet Union, first launch: 1982 – Declined under Russia, but now revived – Similar to GPS: Passive, one-way ranging – 22 working satellites in March 2011 – No significant user base
• Constellation – 24 satellites in 3 orbital planes, 64.8º inclination – 19,100 km altitude, 11 ¼ hour period
• Signals – 3 allocated bands: G1 (1602 MHz), G2: (1245 MHz), G3 (1202 MHz) – C/A-like code: 511 chips, 1 ms code period, 50 bps data – All SVs use same PRN with frequency division multiple access
(FDMA) using 16 frequency channels, reused for antipodal SVs • Plans: full constellation in 2011, evolving capability as CDMA
signals are added <www.glonass-ianc.rsa.ru>
76
Soviet-built GLONASS Aviation Receiver & Tool box (circa 1990)
ASN-16
© 2013 Pratap Misra
77
Summary: Take-Away Points • GPS is based on the old idea of trilateration, but
implemented with the technology of the second-half of the 20th century: space-based radio transmitters, ultra-stable clocks, and spread spectrum signals.
• The success and breadth of GPS applications is attributable largely to “the chip.” The VLSI revolution was well-timed for GPS.
• A GPS receiver measures pseudoranges to the satellites by measuring pseudo-transit times of radio signals. It takes 4 satellites in view (i.e., 4 pseudoranges) in order to estimate position (x, y, z) and time t
• With a clear view of the sky, it’s easy to get positioning accuracy of several meters with a $100 GPS receiver, or relative positioning accuracy of millimeters with a pair of $1000 receivers.
• GPS satellites are 30-watt transmitters 20,000 km away, so the signals reaching the earth are very weak and, therefore susceptible to interference.
78
GNSS = A Satellite Navigation System
79
© 2013 Pratap Misra
• Compatibility – Radio Frequency Compatibility:
no harmful interference among signals
– National Security Compatibility: spectral separation between GPS civil signals and other systems’ signals, and M code
• Interoperability – Two systems are better than
one – Requires attention to signal
designs, system performance, and coordinate frames and time references
Compatibility & Interoperability of Radionavigation Systems
80
Source: Unknown
81
82
83
84
85 Source: A presentation by Japan at the UN International Committee on GNSS Expert Meeting in Montreal on 15 July 2008
86 Source: A presentation by Japan at the ION GNSS 2008 in Savannah, Georgia, on 17 September 2008
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