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Cellular Positioning. Shashika Biyanwila Research Engineer. Outline. What is Cellular Positioning Positioning Parameters Feasible Approaches Identified Implementation Some Trial Results Future Approach of the Research. What is cellular positioning ?.

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cellular positioning

Cellular Positioning

Shashika BiyanwilaResearch Engineer

outline
Outline
  • What is Cellular Positioning
  • Positioning Parameters
  • Feasible Approaches Identified
  • Implementation
  • Some Trial Results
  • Future Approach of the Research

Cellular Positioning

what is cellular positioning
What is cellular positioning ?
  • Determining the position of a Mobile Station (MS), using location sensitive parameters
  • Why ????
    • To provide Location Based Services…

Cellular Positioning

slide4

Applications of cellular positioning

  • Operator services
  • Billing
  • Network management
  • Location based services
  • Wireless Gaming
  • Assistance
  • Roadside assistance
  • Personal or vehicle emergency
  • Alarm management
  • Driving Directions
  • Tracking
  • Tracking criminals
  • Tracking external resources containers etc
  • Monitoring
  • Monitoring delivery process
  • Fleet & freight tracking
  • Personal Child Security
  • Mobile Worker management
  • Information
  • Traffic
  • Nearest service
  • news
  • navigation help
  • advertising
  • Information Directory

Cellular Positioning

slide5

Positioning Parameters

  • Cell-ID
  • Received Signal Strength Intensity (RSSI)
  • Timing Advance (TA)
  • Uplink Time (Difference) Of Arrival (TDOA)
  • Downlink Observed Time Differences (E-OTD)
  • Angle of Arrival (AOA)

Cellular Positioning

feasible approaches identified
Feasible Approaches Identified

Cellular Positioning

1 geometrical approach
1. Geometrical Approach
  • Based on distance measurements
  • Two Steps:

- Distance calculation

- Location Estimation

Cellular Positioning

geometrical approach contd
Geometrical approach contd..
  • Distance Calculation

- Measure the RSSI from neighboring cells

- Apply Propagation models to calculate the distance

  • Propagation Models

- Hata Model

- Extended Hata Model

- Lee’s Model

- CCIR Model

- Walfisch-Ikegami Model (for micro cells)

Cellular Positioning

2 statistical approach
2. Statistical Approach
  • Construct a statistical propagation model for the RSSI
    • Find RSSI at distance d from the transmitter
    • Offsite calibration is necessary to estimate the propagation parameters
  • Define a probability distribution for the RSSI
  • Location estimation problem is solved as an inverse or, rather, inference problem

Cellular Positioning

statistical approach contd
Statistical Approach contd..
  • Log-loss or Log-distance model
  • Gaussian Probability Distribution
  • Propagation Parameter Estimation

- Maximum Likelihood estimation

  • Location Estimation

- Maximum A posteriori Probability

Cellular Positioning

statistical approach cntd
Statistical Approach cntd..
  • Area being considered is divided into several squares
  • A posterior probability of the location be within a square, is calculated for each square

Square with

Maximum A posterior

Probability

Cellular Positioning

3 database correlation method dcm
3. Database correlation Method (DCM)
  • Involves a database of reference fingerprints for the whole area of interest.
  • Fingerprint – a recorded measurement sample from a certain location in the area

GPS coordinates of a location

RSSI (from available cells) in that location

Cellular Positioning

dcm contd

Fingerprint

Measurement

Fingerprint

Test route

DCM contd…
  • How to collect fingerprints?
    • By measurements
    • Using a Network planning tool
  • High sampling resolution is needed.

Cellular Positioning

dcm contd1

Input

Measurement

DCM Algorithm

Estimated

Location

Database

DCM contd…
  • Location estimation
  • Compare the input measurement with reference fingerprints
  • - Using Cost Functions
  • Location of the best matching reference fingerprint
  • Estimated Location

Cellular Positioning

implementation

RSS

RSSI + GPS Reading

Location ?

Measurement Unit

Commands

  • Interfacing Program
  • Database
  • Location Estimation Algorithm
  • Display Program
  • Software environment
Implementation

Hardware Environment

Cellular Positioning

trial results
Urban

- Wellawaththa to Kolpetty

Suburban

- Katubedda to Piliyandala

Rural

- Ibbagamuwa

Trial & Results

Cellular Positioning

slide17
Urban area…..

Cellular Positioning

slide18
Suburban area ……….

Cellular Positioning

rural area
Rural area ……..

Cellular Positioning

future approach of the research
Future Approach of the Research
  • Improvements to the current DCM approach
    • Drawbacks

- Few instances of poor estimations

- Creating, updating & maintenance of the database

    • How To Overcome

- Refined estimation techniques

- Use of a Network planning tool to create fingerprints

Cellular Positioning

slide21

GSM Network

Received Signal Fingerprint

Estimated Location

  • System Information
  • Calibration Fingerprints
  • Digital Maps

Location Estimation using Received Signal Fingerprint & database

Positioning Engine

  • Implementation of a positioning engine and associated services

Services

      • Get your own location
      • Track others – web-based location on a map

Cellular Positioning