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The following web sites contain methods that can be used to secure the transmission
into and out of the robot: COMMUNICATIONS 269
www.postech.ac.kr/cse/hpc/research/webcache/book/security/total.html
www.cs.auckland.ac.nz/ pgut001/links/standards.html
www.cs.auckland.ac.nz/ pgut001/tutorial/
www.11a.nu/security.htm

Popular Communication Channels

In designing the robot, it makes sense to stick to tried and true communication proto-
cols. Several protocols, for both wireless and wired communication channels, are avail-
able and popular. Usually, this means that the hardware and software can be purchased
off-the-shelf. Robots not only need to be designed quickly, but they need to be reliable.
So make sure you check the pedigree of any commercial product. It’s easy to say that a
product conforms to a standard, but most of these standards are so complex that the
newer offerings are not as reliable as the older, more established products.

WIRELESS SYSTEMS

Several wireless data systems have been deployed for some years. We’ll discuss some
of the features and the performance of each one.

Wireless Fidelity (Wi-Fi)

Wireless fidelity (Wi-Fi), or 802.11b, is a wireless version of Ethernet LANs. It uses RF
communication in the 2.4 GHz band and the protocol is documented in 802.11b. Many
people have cards in their laptop PCs that can tap into Wi-Fi portals in stores, busi-
nesses, and public places. This technology makes Internet access available to portable
computer users. It would make a fine communications link for a robot as long as secu-
rity and other issues are handled properly.
The data bandwidth is similar to that of 10BT wired LANs that we discussed earlier
(about 1.5 Mbps or so). The range of transmission is up to a couple hundred feet, but
data speeds can drop after 50 feet. The protocol uses spread spectrum communications,
as discussed earlier. As such, it is adept at overlaying an existing communication spec-
trum and coexisting with the communications traffic in it. Faster versions of the proto-
col are just coming out now. For more information, go to www.wi-fi.org and http://
alpha.fdu.edu/ kanoksri/IEEE80211b.html.