Communication Location Services of Terrestrial Mobile ...
Transcript of Communication Location Services of Terrestrial Mobile ...
ION International Technical Meeting - September 19-22 2000 - Salt Lake City 1
Synergies Between Satellite Navigation andLocation Services of Terrestrial Mobile
Communication
Günter W. Hein, Bernd Eissfeller, Veit Oehler, Jón Ó. Winkel
Institute of Geodesy and NavigationUniversity FAF Munich
ION 2000 International Technical MeetingSalt Lake City
September 19-22 2000
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OVERVIEW
• Targets of communication and satellite navigation• Positioning using mobile communication• Implementation with GSM and UMTS• Error budget and simulations• Rough estimate on required infrastructure• Conclusions
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MOBILE COM vs. SATNAV 1
Phenomena Communication Navigation
Basic function of thesystem
Error free transmission of largeamount of data
Global 3D positioning and timingwith high accuracy and integrity
Quality parameter BER = 10-3 to 10-6 2drms = 0.01m to 100m
Connection Up- and Down-Link Down-Link
Coverage Terrestrial Terrestrial, airspace, maritime,space
Number of transmitters Large: > 100.000 global Small: 20 – 30 globalRequirements on Rx –Tx configuration
Contact to one and only one Tx Simultaneous contact to as manyTx as possible (at least 4)
User data rate High: > 2 Mb/s for UMTS Low: 50 – 200 b/s
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MOBILE COM vs. SATNAV 2
Phenomena Communication Navigation
System planning Maximize data rate and num-ber of users
good geometry for positioning (DOP)
Propagation path Non-LoS not critical, evendesired
LoS essential
Multipath, number ofreflectors
Not critical Critical
Power control Necessary Not necessaryRequired synchroniza-tion
0.25 Bit or Chip < 0.01 Chip
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POSITIONING USING MOBILE COMMUNICATION 1
Network-based positioning
Handset-based positioning
Hybrid positioning
Positioning done using signals andhardware only of the wireless systemPositioning done using an independentpositioning system (GNSS etc.)Positioning done using several inde-pendent positioning systems (GNSS,LORAN-C etc.)
Self positioning
Remote positioning
All measurements and calculations re-lated to positioning performed insideMSAll measurements and calculations re-lated to positioning performed insidenetwork
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POSITIONING USING MOBILE COMMUNICATION 2
Handset-based positioning• Each sensor operates independently: no integration
– Such handys already available• „Wireless Assisted GNSS (GPS)“
– First implementations and experiences, also indoors• Integration of handset and GNSS functions
– First investigations
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GEOMETRICAL PRINCIPLES• Time of Arrival (ToA)
MS at intersection of circlesSynchronisation of BSs and MSrequired
• Time Diff. of Arrival (TDoA)MS at intersection of hyperbolasSynchronisation of BSs required
• Angle of Arrival (AoA)MS at intersection of directed linesNo synchronisation required
(c) AoA
A
B
X
θθθθA
θθθθB
(a) ToA
X
A B
C
ρρρρAρρρρB
ρρρρC
(b) TDoA
A
B
CX
TDOAC-A
TDOAB-A
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WHICH CHANNEL IS SUITABLE FOR LCS ?
Parameter Up-LinkControl channel
Down-LinkControl channel
Self positioning No YesNumber of users Limited UnlimitedMAI potential High LowVariation of C/No due to powercontrol
Large Moderate
Hand-over Easy DifficultModification of signal No Yes (IPDL)Capacity impact Negligible PresentHandset modification No Yes
Down-Link (forward)
Up-Link (reverse)
Mobile com.system
Control channels (CCHs)
Traffic channels (TCHs)
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IMPLEMENTATION IN GSM AND UMTS
GSM900 UMTSMultiple Access FDMA: 200 kHz bandwidth per
carrier frequencyTDMA: 8 channels per carrier freq.
FDMA: 5 MHz bandwidth per carrier freq.CDMATDMA: 16 channels
Frequencies DL: 890-915 MHzUL: 935-960 MHz
DL: 2110-2170 MHzUL: 1920-1980 MHz
Bit rate 271 kbit/s 2 Mchips/s
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IMPLEMENTATION IN GSM
Correlation method– 26 training bits in „Normal burst“– 64 training bits in „Synchronization burst“
Training sequence26 bits
Coded data57 bits
Coded data57 bits
Stealing flag2 bits
Stealing Flag2 bits
Tail bits3 bits
Tail bits3 bits
Guard period8.25 bits
Normal burst
Chip length 48/13µs or 1.1km
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IMPLEMENTATION IN UMTS 1
BS #1
BS #2
BS #3
BS #4
BS #n
IP #i
IP #j
Burst Burst
Burst
Burst
Burst
Burst
Burst
Burst
IPDL
Channel access by CDMA
Problem: Near-far effect
Proposed solution:
Implementation of idle periods
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IMPLEMENTATION IN UMTS 2Influence of IPDL on measurement noise
(Channel parameters according to a study of Samsung)
25
30
35
40
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55
60
0.001 0.010 0.100 1.000
Duty cycle
S/N
o [d
BH
z]
0
10
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30
40
50
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70
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90
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capa
city
[%]
Acquisition threshold (34 dBHz)
3% IPDL
Urban (1000m)
Suburban (3000m)
Rural (20 km)
Capacity
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0
-300
-200
-100
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0 200 400 600 800 1000 1200 1400 1600
Geometric delay [m]
Mul
tipat
h er
ror [
m]
-20
-15
-10
-5
0
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0 50 100 150 200 250 300
Geometric delay [m]
Mul
tipat
h er
ror [
m]
GSM
MULTIPATH ERRORS
UMTS
Multipath error envelopes (Multipath errors due to superposition of a direct with an indirect signal,relative attenuation: 0.5)
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ERROR BUDGET
Error source GSM UMTSMeasurement noise 270 m 18 mMultipath(*) 0-250 m 0-17 mTroposphere 0.3-3 m 0.3-3 mSynchronization ofnetwork/handset
3-6 m 3-6 m
Oscillator error 7.5 m 7.5 mTotal error (1 sigma) 270-380 m 19-26 m
(*) Not calculated with NLoSNLoS causes errors due to multipath corresponding to the geometric delay
Position error = HDOP*Ranging error*2 (2dRMS)
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SIMULATIONS• Extension of IfEN´s SatNav End-to-End S/W simulator
– UMTS signal structure• Two test areas:
– Stuttgart downtown: High density of BSs, microcells– Oedekoven (suburb of Bonn): Rural BS structure
• Calculations (only horizontal position possible):– Number of “visible” (receivable) base stations– Geometry factors– Densification of MobCom network:– Number of necessary BSs for area-wide positioning– GNSS (GPS) vs. MobCom
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TEST AREASOEDEKOVEN (NEAR BONN)1.5 km E-W, 1.8 km N-S31 Base stations
OEDEKOVEN (NEAR BONN)1.5 km E-W, 1.8 km N-S31 Base stations
DOWNTOWN STUTTGART3.0 km E-W, 3.0 km N-S178 Base stations
DOWNTOWN STUTTGART3.0 km E-W, 3.0 km N-S178 Base stations
Grid: 200m x 200m, 1.5m above bottomGrid: 200m x 200m, 1.5m above bottom
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NUMBER OF RECEIVED BSsStuttgartOedekoven
< 3 BSs (63.9%)3 BSs (9.7%)
> 3 BSs (26.4%)
< 3 BSs (72.2%)
3 BSs (5.6%)
> 3 BSs (22.2%)
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GEOMETRY FACTORS
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Number of directly visible BSs HDOP (mostly > 100)
Number of directly visible BSs HDOP (mostly > 100)
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NETWORK DENSIFICATION (OEDEKOVEN) 1
Network structure (4+9) Network structure (30+60)
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NETWORK DENSIFICATION (OEDEKOVEN) 2
Network structure (30) Network structure (90)
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MOBCOM vs. GNSS (GPS)Directly visible SVs and HDOP (for GPS)
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• Area-wide positioning using MobCom with accuracy < 50m– Increasing the NUMBER of BSs with factor 2-3 due to geometry– 40 000 BSs x $ 50 000… $ 90 000 = $ 2 … 3.6 billion
• Synchronization of BSs (with higher accuracy) necessary– DCF77 and Quartz not sufficient (10-7s) > Rubidium or GPS– 20 000 BSs x $ 5 000 = $ 100 million
• Equipment of MobCom network with Location Measurement Units (LMU)– Per 3-5 cells 1 LMU; approx. $ 7 000 … $ 10 000; 20 000 cells in D (Germany)– Investment costs for LMUs only D: $ 50 ... 70 million
• Total costs 2D positioning 100m (2drms) in D: $ 2.1 … 3.8 billion• For comparison: USA >$ 5 billion (www.fonefinder.com/Introduction.html)
ROUGH ESTIMATE ON REQUIRED INFRASTRUCTURE
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CONCLUSIONS• Existing potential for 2D positioning in UMTS up to approx.
100m (2drms)• Substantially limitations due to terrestrial geometry• Total costs for LCS in existing network: > $ 150 million• Total costs for area-wide LCS in D: $ 2.1 ... 3.8 billion per
network• Only for particular land user groups with limited requirements,
not applicable for aero- and astronautics• Integrity and continuity not yet considered