Finding Solutions for GPS Indoors

By Fady Rizk

What’s GPS?Global Positioning SystemThe idea has been there since the 70’s

Became available for commercial use in 1993

GPS Receiver

How?Receiver receives signals from satellites

Using the trilateration methodThen computes the dataOutputs the results on a map

Trilateration

The Problem

GPS receiver work outdoors

…but not indoors

Why?

1- Suffers a low signal-to-noise ratio

2- Fails to identify a correlation peak

3- Results in failing to identify a location

Problem Conclusion

Receiver finds it difficult to detect any signal from the

satellites due to reflection, diffraction, fading, refraction, signal

attenuation or total obstruction

The Need:Finding people in buildingsFinding workers in cavesFinding locations in huge buildings

Finding lost soldiers

What to do?

High Sensitivity GPS receiverThe Beacon (ultrasonic sensor)The Unscented Kalman Filter

(UKF)

High Sensitivity GPS (chip/receiver) Makes the receivers process signals

with the strength of -180 dBW or below

Captures 70% of the available signals

Increases the carrier to noise ratio

The Active Beacon (ultrasonic sensor) Easy signal-processing Estimates a stable and fast

localization for a moving object Exhibits robust performances in noisy

environments Operates with a low sampling-rate

The Unscented Kalman Filter (UKF)

Just a better filter and algorithm to use

Overcomes severe disturbance for sensor measurement

Does not fix the delay

Research Idea

Combining the researchers’ solutions and experiments into one

AndFollow researcher's suggestions to fix

problems

Experiment Environment A building’s last floor Preferably a building that has concrete

structure Three measurement positions:1- A terrace surrounded by four walls, with no

roof2- Room with a roof, with the dimensions of at

least 10.2 x 11.2 x 4.2 meters 3- A small corridor surrounded by multiple

walls

Expected Results

The receiver to not suffer of a low signal-to-noise ratio (HS GPS)

Receiver process signals with the strength of -180 dBW or below (HS GPS)

70% of the signals and fix the pseudo range problem

a stable and fast localization

How to value the results?The closer it gets to the GPS receiver’s behavior outdoors, the more this experiment is successful

If the outcome of this experiment shows better and more accurate

results than what researchers did, the experiment is also considered as a

success

Thanks for your attention