wireless ad hoc networking

580 Wireless Ad Hoc Networking
interchangeability, scalability, modularity, programmability, and network
security. Largely, these attributes can be considered under two domains,
namely, “run-time surface” and the “offline surface.” The run-time surface
embodies the response time, real-time control, intrinsic safety, and operational
intelligence, whereas the offline surface embodies aspects such as
interoperability, interchangeability, and scalability. 9
22.4 Standards, Frequency Bands, and Issues
RF technology uses radio waves to carry control signals. Different wireless
protocols and methods arose with different RF technologies. These include
traditional radio transceivers, cellular telephones, and laptop PCs. Some
wireless protocols are defined and administered by the IEEE as part of
its 802 standards, which are being developed to achieve increased speeds
and new functions. The primary benefits of wireless transmission have
led to a number of solutions. These solutions range from voice-oriented,
large-scale cellular networks, to data-oriented solutions like wireless LAN
(WLAN), wireless personal area networks (WPAN), and wireless sensor networks
(WSN). WLAN systems, like the IEEE 802.11 family of standards, are
designed with high data rates in terms of tens of Mbit/s over ranges of
a kilometer. These parameters provide the user with access to Ethernet.
WPAN systems, such as Bluetooth and IEEE 802.15.4 can connect devices
wirelessly and are considered energy-efficient. 10 They also support medium
data rates in the order of hundreds of Kbit/s to a few Mbit/s and have ranges
in the order of a few meters.
Bluetooth is very popular and is a radio standard mainly designed for
low power consumption, short range, and with a low-cost transceiver
microchip in each device. Bluetooth-based network, called piconet, has
already gained popularity. A piconet is a network of devices connected
in an ad hoc fashion. A piconet is formed when a portable PC and cellular
phone connect each other, and it supports up to eight devices. Within
the net, one device acts as the master while the others act as slaves for
the duration of the piconet connection. A piconet is also referred to as
PAN. Although, the main applications of Bluetooth technology are desktops
and laptops, printers, mice and keyboards, cell phones, personal digital
assistants (PDAs), and other handsfree devices, it can support other wireless
networks. The standard also includes support for more powerful, but
certain data logging equipment that can transmit data to a computer via
Bluetooth and can also be used for remote controls in the place of infrared
which was traditionally used.
Wireless communication takes place in different frequency bands. The
fundamental physical laws restrict the transmission power. The 2.4 GHz
Industrial Scientific and Medical (ISM) band is a common example. Some
proprietary protocols use 900 MHz band. Although this band inherits low