Context-Aware Applications - Guide to Cloud Computing for Business and Technology Managers - page 517

TABLE 23.2
Location Enablement Technologies

Technology Description Advantages Disadvantages

Network based
Cell of
origin
(COO)

Information generated
about the cell
occupied by a user

RF technology
Inexpensive—uses
existing network
No handset
modification
Fast implementation
No consumer behavior
change

Low resolution

Angle of
Arrival
(AOA)

Measures angle of
signal from mobile
device to cell towers
Minimum of two cell
sites required

FF technology
No handset
modification
No consumer behavior
change

Expensive network
modifications required
Resistance toward more
antennas in
neighborhoods
Line-of-sight constraint
Medium resolution (not
less than 150 m)

Time
Distance of
Arrival
(TDOA)

Triangulates at least
three stations to
measure and compare
arrival time of signal
from a user

RF technology
No handset
modification
No consumer behavior
change

Line-of-sight constraint
Expensive
Medium resolution
Appropriate for CDMA

Enhanced
cell ID
(E-CID)

Software-based
solution that compares
list of cell sites
available to user and
checks for overlaps

RF technology
Line of sight not
required
Moderate cost to
upgrade

Works only with GSM
Some modification
required in handset
and network

Handset based
Global
Positioning
System
(GPS)

Radio navigation
system comprising
low-orbit satellites.
Triangulation by
measuring the time to
communicate with
three satellites

FF technology
Very accurate, 1-5 m,
95% precision
Not dependent on
network

Line-of-sight issues
Significant handset
Handset modification
May require consumer
behavior change
modifications

Hybrid technology
Enhanced
observed
time
difference
(E-OTD)

Similar to TDOA, but
handset calculates the
location

RF technology
Accuracy of 50-125 m
Some behavior change

Suited for GSM only
Network and handset
modification
Cell coverage necessary

Assisted
global
positioning
system
(A-GPS)

Processing done by
network while using
the satellites

RF technology
Moderate modification
to handset
Line-of-sight
constraint reduced

Significant changes to
network