wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

4-2 Industrial Communication Systems
WPAN
WLAN
WiMax
tower
(UMTS, GPRS, GSM)
WMAN
WWAN
FIGURE 4.1
Wireless network classification (WPAN, WLAN, WMAN, WWAN).
• Wireless metropolitan area networks are a type of network that connects several Wireless LANs.
WiMAX is the term used to refer to WMAN and is covered in IEEE 802.16d/802.16e.
• Wireless wide area networks with technologies such as universal mobile telecommunication system
(UMTS ), general packet radio service (GPRS), and global system for mobile communication (GSM).
To further increase radio coverage for clients and facilitate ease of movement, wireless mesh networks
(WMN) are used. WMNs span all segments and are a completely flat and nonhierarchical organization
formed to cover all areas, and for this reason it is outside the previous classification. A WMN has been
defined as a network composed of mesh routers and mesh clients. Mesh routers have minimal mobility
and form the backbone of the network, and the mesh clients may be stationary or mobile, and can form
a client mesh network among themselves and with mesh routers. In this scheme, each node operates not
only as a host but also as a router, forwarding packets on behalf of other nodes that may not be within
direct wireless transmission range of their destinations [AWW05]. In mesh networks, full physical layer
connectivity is not required; a mesh network employs one of two connection arrangements, full mesh
topology or partial mesh topology. As long as a node is connected to at least one other node in a mesh
network, it will have full connectivity to the entire network because each mesh node forwards packets
to other nodes in the network as required.
There are many different types of mesh networks. Mesh networks can be wired or wireless. For wireless
networks, there are ad hoc mobile mesh networks or wireless sensor networks,* and permanent
infrastructure mesh networks. Regarding radio transmission, there is another classification: single
radio mesh networks, dual-radio mesh networks, and multi-radio mesh networks.
WMNs can widely find applications in WLANs, WMANs, WPANs, and wireless sensor networks
(WSNs). Major industrial organizations are actively working on introducing multi-hop mesh elements
in their next generation standards. For example, IEEE has created a working group to define
how the mesh works in 802.11 networks (WLAN). 802.11s [AESSM] networks also include two routing
* In ad hoc networks and sensor networks every node functions as a router.
© 2011 by Taylor and Francis Group, LLC