صفحه 1:
CSCE 5013: Hot Topics in Mobile and Pervasive
Computing
Nilanjan Banerjee
University of Arkansas
Fayetteville, AR
nilanjan.banerjee@gmail.co
m
Hot Topic in Mobile and Pervasive Computing
صفحه 2:
What is localization, aka location?
absolute location
(lat, long)
relative location
context location
صفحه 3:
Why should I care about localization?
social application
advertisements
podcasting
صفحه 4:
What can I use to localize my phone?
GPS , Cell tower
اس خن OS Wi-Fi
0 ۱
Bluetooth
Ambience
RFID
صفحه 5:
How does these technologies work (Centroid
scheme)
position of the
Ss
istance from BSs
صفحه 6:
Position of the BSs
* Find position of the APs and cell towers
— Based on databases already available (Placelab
Intel Research)
— Cell phone companies know the position of their
cell towers
صفحه 7:
Distance measures
* Received Signal Strength Indication (RSSI)
— Correlation between RSSI and distance
re م
5 ۳ 2
لاه
مكعم لدبي
ene
Distance song walk meters)
* Time to propagation
— Amount of time for signal to propagate from
source to destination
— Distance = time * speed of propagation
صفحه 8:
Alternate method purely based on profiling...
* Take extensive measurements of your environment
* War driving
* Similar to what Jonathan and Warner are doing
* Collect tuples <location, <AP1, signal strength> , <AP2,
signal strength>, ....>
* Scan and look for APs or cell towers
* Match with your measurements
* Compare with the signal strength and set of APs in the
scan and your measurements
* Choose location which matches closely to the collected
measurements
صفحه 9:
Relative positioning of individuals
Placing people in a two dimensior
plane
Application to localization in ad h
networks
luetooth/Wi-Fi/sound/Infrared
صفحه 10:
Trade-offs between some of these schemes...
Energy Energy hungry No Energy cost low energy
hungry Moderately Very inaccurate accurate
Very accurate accurate Works outdoor very short
Works Works outdoor and indoor range
outdoors and indoor
10
صفحه 11:
11
Challenges...
High Accuracy of
localization
Energy-
Efficiency
Distance
measure
RSSI?
Location
Privacy
صفحه 12:
Papers we will cover under localization
SurroundSense:
Mobile Phone Localization via Ambience
Fingerprinting
Sherlock:
Automatically locating objects for human
BeepBeep:
A High Accuracy Acoustic Ranging System
using COTS Mobile Devices
12
Ambient
sources
RFID
Sound
صفحه 13:
13
Next class
* Reviews due for the following paper
* SurroundSense paper
* Review due by 11:59 p.m. tomorrow
* Extra class on iptables tomorrow in 239 from 3:30-
4:30
