35282752 positioning techniques in 3g networks
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8/3/2019 35282752 Positioning Techniques in 3G Networks
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Positioning Techniques in 3G
Networks
Pushpika Wijesinghe
Independent Study Presentation
Supervisor:
Prof (Mrs.) Dileeka Dias
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Outline
• 3G mobile Networks
– 3G Standards
– Basic Network Architecture
• Positioning Parameters in 3G networks
• Positioning Techniques in 3G networks
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3G Mobile Networks
• Intended to provide Global Mobility
Source: http:// www.ccpu.com
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3G standards
IMT-2000
WCDMA(UTRAFDD)
TD-CDMA(UTRATDD)
Cdma2000(multi-carrier)
UWC 136(Single-carrier)
DECT(Frequency Time)
3GPP 3GPP2 UWCC ETSI
DECT
Paired spectrum
Unpaired spectrum
UMTS
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Basic Network Architecture
Source: http:// www.ccpu.com
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To Access
Network
Core Network ..
Core
Network
To PSTN
Network
To Packet
Network SGSN GGSN
MSC GMSC
AuC HLR EIR
PS Domain
CS Domain
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Positioning Parameters
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Received Signal Code Power (RSCP)
• Received power on one code measured on
the Common Pilot Channel (CPICH)
• A downlink measurement, carried out by theUE
• Can be obtained in idle mode and active
mode
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Received Signal Strength (RSS)
• The received wide band power, including
thermal noise and noise generated in the
receiver• RSSI describes the downlink interference
level at the UE side
• Measurable by the UE• Can be measured in active mode only
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• Time Difference of System Frame Numbers
(SFN) between Two cells
TCPICHRxj – TCPICHRxi
TCPICHRxj - Time when the UE receives one Primary CPICH slot
from cell j
TCPICHRxi - Time when the UE receives the Primary CPICH slot
from cell i that is closest in time to TCPICHRxj
• Measured in idle mode or active mode by the UE
SFN-SFN observed time difference
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Round Trip Time (RTT)
• Corresponds to the Timing Advance Parameter in GSM RTT = TRX – TTX
TTX - Time of transmission of the beginning of a downlink DPCH frame to a
UETRX - Time of reception of the beginning (the first detected path, in time) of
the corresponding uplink DPCCH frame from the UE
• Measurements are possible on Downlink DPCHtransmitted from NodeB and Uplink DPDCH received in
the same NodeB
• Measured in active mode only
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Angle of Arrival (AoA)
• Arrival angle of the signals from the mobile station at
several NodeBs
• Special antenna arrays should be equipped at the
NodeBsNodeB with directional
antenna
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Positioning Techniques
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Positioning Techniques
Positioning Techniques
Cell ID Based Methods
OTDOA with Enhancements
Database Correlation Method
Pilot Correlation Method
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Cell ID Based Method
• Simplest method
• MS position is estimated with the knowledge of serving
NodeB
• Position can be indicated as:• Cell Identity of the serving cell
• Service Area Identity
• Location co-ordinates the serving cell• Accuracy of the estimation depends on the coverage
area of the cells
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Enhancements to Cell ID
• Wide range of enhancements for the Cell ID
based method
– Cell ID + RTT (Round Trip Time)
– Cell ID + Reference Signal Power Budget
– Cell ID + RSCP (Received Signal Code
Power)
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Cell ID + RTT (Round Trip Time)
• Identical to Cell ID+TA (Timing Advance) method inGSM
• Accuracy of RTT measurements in UMTS is significantly
higher (36m)
• RTT is used to calculate the distance from the NodeB to
MS using propagation models
• Performance can be enhanced by incorporating the RTT
measurements from all Node Bs in the Active Set
• Accurate RTT measurements through Forced Hand Over
(FHO)
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Cell ID + RTT (Round Trip Time)
Location Estimation:
• Constrained least-square (LS) optimization for estimatingthe position (by Jakub Borkowski & Jukka Lempiainen)
– Assume an initial position (Geographical mean of hearableNodeBs)
– Minimize the function F(x)
x = column matrix consisting the coordinates of the MS (x,y).
P = A Positive Scalar
N
i i
N
i
i xg
P x f xF 1
1
1
2
)(
1)()(
)()( x f xg ii
0)()()(22 y y x xd x f iiii
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Location Estimation:
- Location estimation is done according to the following
recursion
- Continue until the following condition is fulfilled, for a
defined threshold
Cell ID + RTT (Round Trip Time)
)(1 k xk k xF x x
t xF k x )(
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Cell ID + RTT (Round Trip Time)
• Some simulation results for urban & suburban
areas (by Jakub Borkowski & Jukka Lempiainen)
Topology Urban Suburban
67% 95% 67% 95%
6-sector / 650 75 m 200 m 50 m 150 m
6-sector / 330 60 m 220 m 55m 170 m
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Cell ID + Reference Signal Power Budget (RSPB)
•Coverage area of a cell can be determined by usingRSPB
• RSPB gives information about
- Node B transmitted power
- Isotropic path loss
- Coverage threshold at coverage area border for agiven location probability
- Cell radius for indoor and outdoor coverage
• SRNC may compare the received power levels with thepower budget to accurately position the UE
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OTDOA method with Enhancements
• Relative timing offset of the CPICH associated withdifferent Node Bs are used
• Each OTDOA measurement describes a line of constant
difference (a hyperbola) along which the MS may belocated
• MS's position is
determined by theintersection of hyperbolas forat least three pairs of NodeBs
Standard OTDOA Method
Source:
[3] 3GPP TS 25.215:
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Standard OTDOA method
Features
• The accuracy depends on the precision of the timing
measurements
• Timing synchronizations of different NodeBs is essential
• Best results are when the Node Bs equally around the MS
Drawbacks
• Hearability Problem Serving NodeB drowns the signals
from distant NodeBs
Solution
• Get the assistance of secondary services
OTDOA method with Enhancements
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OTDOA method with Enhancements
• In UMTS NodeB transmissions are synchronously
ceased for a short period of time - Idle Period
• Terminal can measure neighbor NodeBs during IdlePeriods
• Maximizes the hearability of distant pilots
• Two techniques – Standard IPDL
– Time Aligned IPDL (TA-IPDL)
Use of Idle Periods in Down Link (IPDL)
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OTDOA method with Enhancements
Use of Idle Periods in Down Link (IPDL)Standard IPDL - Pseudo random idle slots
Time Aligned IPDL (TA_IPDL) - Time Aligned Idle Slots
Source: [10] 3GPP TSG-RAN WG1 doc
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OTDOA method with Enhancements
Time Aligned IPDL (TA-IPDL) Method • During the „common‟ idle period each node B transmits a
signal ONLY useful for location estimation, randomly,
pseudo-randomly or periodically
• OTDOA of these common pilots is measured in the MS for
different Node Bs
• Positioning is done as in the standard OTDOA algorithm
• Drawbacks
- added complexity to the network operation
- reduced communication efficiency
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Time Aligned IPDL (TA-IPDL) Method
Area 67 % error 90 % rms error
Rural 8 m 6 m
Sub urban 6 m 5 m
Urban-B 44 m 39 m
Urban -A 95 m 83 m
Bad Urban 218 m 193 m
- Simulation Results (TSG-RAN Working Group 1)
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OTDOA method with Enhancements
• Uses virtual blanking of
the Node B downlink
signals in the software
domain based on theprinciples of interference
cancellation
• Significantly enhances
hearability than in IPDL,
using signal processing
techniques
Use of Cumulative Virtual blanking (CVB)
Source:
[12] http://www.3gpp.org/ftp/tsg_ran/TSG_RAN/RP-020372.pdf
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Use of Cumulative Virtual blanking (CVB)
• Downlink signal are measured simultaneously at the handsetand at Node Bs
• Handset – Received signal snapshots
• NodeB - Time co-incident snapshots of the transmitted
signals
• Measurements are transferred to the location server
• Location server extracts the OTD of weaker NodeBs‟ signals
by attenuating the interfering signals one by one
• Multiple Node B signals are blanked allowing weaker ones to
be measured
• Positioning is done using standard OTDOA algorithm
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Use of Cumulative Virtual blanking (CVB)
• No impact on downlink capacity
• Median number of hearable Node Bs for CVB is
roughly double that for IPDL
• Much more robust in the presence of multipath
• Operational complexity is reduced compared with
IPDL
Features
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Use of Cumulative Virtual blanking (CVB)
Some preliminary results obtained through trials in
several sites of a UMTS network (TSG-RAN Group)
Site Time Error
1 16:26 22.8 m
2 16:43 27.6 m
3 17:11 16.9 m
4 17:13 5.7 m
5 17:16 26.2 m
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Database Correlation Method (DCM)
• Based on a pre-measured database oflocation dependent variable
• DCM in UMTS utilizes Power Delay Profile
(PDP) of locations (GSM used RSSI)
• An entry of the database consists of:
– location coordinates (Lat, Lon)
– serving Node ID
– Power delay profile from that Node
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Database Correlation Method (DCM)
• In location estimation PDP from the serving NodeB iscorrelated with the PDPs stored in the database
• The point with the highest correlation coefficient is chosen
as the location estimate
• RTT measurement
from same NodeB is
used to limit the
number of correlation
points
Source: [8]. “Database correlation method for UMTS location”
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Database Correlation Method (DCM)
• Advantages
– Avoids problems related to Multipath Propagation
• Drawbacks
– Delay Profile Measurements are not standardized in
3GPP, thus requiring software changes at the MS
– Reporting of such measurements to the location
server in the network is also not standardized – Higher cost in creating database
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Database Correlation Method (DCM)
• Some simulation results in urban UMTS network in
comparison with OTDOA method -(by Suvi Ahonen & Heikiki Laitinen)
67 % 95%
DCM 25 m 140 m
OTDOA 97 m 620 m
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Pilot Correlation Method
• Based on a database with pre-measured samples ofReceived Signal Code Power (RSCP) Measurements of
visible Pilots
• Database Preparation
– Area is divided into small regions (positioning
regions)
– Size of the region depends on the desired accuracy
– For each positioning region, the most probable
Common Pilot Channels‟ RSCP measurements are
stored.
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Pilot Correlation Method
Database Preparation
• An entry of the database contains:
– The positioning region
– Visible Common Pilot Channels
– RSCP of each pilot
• Can be created automatically from log files of
the measurement tool
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Pilot Correlation Method
Location Estimation
• Measured RSCP of visible pilots are compared with all
samples stored in the database
• Least Square Method is applied for comparison
Si – Value of the ith field of the stored sample
mi – Value of the ith field of the measurement
N - Number of fields in the vector
• Estimated location coordinates of the middle
point of the position region having smallest SLMS
N i
i
N i
ii LMS mSS2)(
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Pilot Correlation Method
Advantages
• An entirely network-based approach and doesn‟t require
any hardware or software modifications in the MS
• Deployment costs are minimized by the use of
standardized measurements and procedures
• Since the database can be created automatically using
the log files of the measurement tool, no additional effort
is needed in database formation
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Pilot Correlation Method
• Some results obtained in real network conditions in anurban UMTS network in Finland….
Test Route 67 % 95 %
Route -1 70 m 130 m
Route -2 90 m 195 m
Route -3 90 m 180 m
- By Jakub Borkowski & Jukka Lempiainen
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Other Positioning Techniques
• Positioning Element OTDOA method
• Angle of Arrival Method
• Uplink Time Difference of Arrival Method
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Summary
• 3G Mobile Networks
• Positioning Parameters in 3G Networks
• Positioning Techniques – Enhancements to Cell ID based methods
– Time based methods
• OTDOA methods and enhancements
– Database Correlation method
– Pilot Correlation method
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References
[1] http://www.three-g.net/3g_standards.html (accessed on 15.05.200710.30 a.m)
[2] Sumit Kasera, Nishit Narang, “3G Networks Architecture, Protocols and
Procedures”, Tata McGraw-Hill Professional Networking Series.
[3] 3GPP TS 25.215: Universal Mobile Telecommunications System
(UMTS); Physical layer; Measurements (FDD), version 7.1.0 Release 7.[4] WCDMA RNP and RNO Training material, Part I and Part II, Huawei
Technologies Company limited.
[5] 3GPP TS 25.305, “UMTS; UE positioning in Universal Terrestrial RadioAccess Network (UTRAN); Stage 2,” ver. 7.1.0, Rel. 7,
http://www.3gpp.org.
[6] Jakub Borkowski , Jukka Lempi¨ainen, “Practical Network-BasedTechniques for Mobile Positioning in UMTS”, Institute of CommunicationsEngineering, Tampere University of Technology, Finland.
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[7] J. Borkowski, J. Niemel¨a, and J. Lempi¨ainen, “Performance of Cell
ID+RTT hybrid positioning method for UMTS radio networks,” inProceedings of the 5th European Wireless Conference, pp. 487 –492,Barcelona, Spain, February 2004.
[8] S. Ahonen and H. Laitinen, “Database correlation method for UMTSlocation,” in Proceedings of the 57th IEEE Vehicular Technology
Conference, vol. 4, pp. 2696 –2700, Jeju, South Korea, April 2003.[9] J. Borkowski and J. Lempi¨ainen, “Pilot correlation method for urbanUMTS networks,” in Proceedings of the 11th European WirelessConference, vol. 2, pp. 465 –469, Nicosia, Cyprus, April 2005.
[10] 3GPP TSG-RAN WG1 doc. No R1-99b79, “Time Aligned IP-DLpositioning technique,” 1999, http://www.3gpp.org/ftp/ tsg ran/WG1
RL1/TSGR1 07/Docs/Pdfs/R1-99b79.pdf.[11] 3GPP TSG-RAN WG1 doc. No R1-00-1186, “Initial Simulation
Results of the OTDOA-PE positioning method,” 2000,http://www.3gpp.org/ftp/tsg ran/WG1 RL1/TSGR1 16/Docs/ PDFs/R1-00-1186.pdf.
References
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[12] 3GPP TSG-RAN Meeting No. 16, TSG RP-020372, “Software
blanking for OTDOA positioning”, June 2002, Marco Island, Florida,USA,
[13] P. J. Duffett-Smith, M. D. Macnaughtan, “Precise UE Positioning inUMTS Using Cumulative Virtual Blanking,”, 3G Mobile CommunicationTechnologies, May 2002, Conference Publication No.489.
[14] Lames J, Caffery Jr, Gordon L.Stuber, Georgia lnstitute ofTechnology, “Overview of Radiolocation in CDMA Cellular Systems”, IEEE Communications Magazine, April 1998.
[15] Jakub Borkowski, Jarno Niemelia, Jukka Lempiainen, “ LocationTechniques for UMTS Radio Netwroks”, Presentation of Reasearch
Activities, Institute of Coommunications Engineering, Tampereuniversity of Technology, Tampere, Finland.
[16] Jakub Borkowski , Jukka Lempiäinen, “Novel mobile-based locationtechniques for UMTS”, Institute of Communications Engineering,Tampere University of Technology, Tampere, Finland.
References
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Questions?
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