Information Technology Reference
In-Depth Information
Table 1: Wireless technologies main features.
Name
Application
Features
Modulation
Max rate
Issuer
DSSS
(802.11b)
11 Mbps
Broad
band, high
speed
802.11
WLAN
IEEE
OFDM
(802.11a/g)
6--108
Mbps
1 Mbps
(SWAP 1.0)
HomeRF
SOHO
Low cost
FHSS
HRFWG
2 Mbps
(SWAP 2.0)
Broad
band, low
cost
Cable
replacement
Bluetooth
FHSS
1 Mbps
BT-SIG
Table 2: Wireless technologies comparison.
Name
Max rate
Rel. cost
Net supp.
Range
Currents
802.11
108 Mbps
Med/Hi
TCP/IP
> 50
m
10-400 mA
HomeRF
2 Mbps
Medium
TCP/IP
> 50 m
1-300 mA
Bluetooth
1 Mbps
Med/Low
PPP
< 10 m
1-60 mA
IrDA
16 Mpbs
Low
PPP
< 2 m
10 µA to
300 mA
Table 2 is the summary of described wireless technologies. It shows the
maximum bit rate, the relative cost of devices, the supported protocols for
integration with data and/or voice networks, the operational range and the
approximate power consumption.
7
RFID
At the end of this chapter, we decided to spend a paragraph for radio
frequency identification (RFID), even if it is a wireless technology not
intended for communications. Owing to its features, RFID became one of the
most used wireless technology in pervasive systems implementations. In fact,
due to its flexibility, it can be used in several different ways than those it was
designed for.
RFID technology is a contactless identification that can read labels which
hold data. RFID was initially developed for items detection and access
control applications. It is particularly effective in industrial production and,
more generally, in environments where bar-coded labels are difficult to read.
RFID can detect moving objects, so it is widely used in the transport
management field, for the automatic identification of vehicles and cargo.
