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

Routing in Wireless Networks 4-3
mechanisms, through an Ad hoc On-Demand Distance Vector (AODV) and Optimized Link-State
Routing Protocol (OLSR) hybrid solution [MZKD04]. The standard 802.16 (WMAN) supports a mesh
form of working [LMAN04], although it is not compatible with the standard IEEE 802.16e for wireless
metropolitan networks. The IEEE 802.15 standard defines the physical layer and media access control
(MAC) of the WPANs and the working group IEEE 802.15.5 [TG5] is studying how to establish a mesh
architecture in this type of network. Figure 4.2 shows how the four types of wireless networks (WPAN,
WLAN, WMAN, WWAN) and the WMNs live side by side. In the case of WMNs, mesh routers are
distinguished from mesh clients.
If we use the term WMN in a wide sense to denote any kind of multi-hop network, regardless of
the wireless technology used or the hardware features of the related devices, an ad hoc network can
be understood as a subset of WMNs, since no infrastructure exists in an ad hoc network [AWW05].
A mobile ad hoc network (MANET) is a collection of wireless mobile hosts forming a temporary
network without the aid of any centralized administration or standard support services. In such an
environment, it may be necessary for one mobile host to enlist the aid of others in forwarding a packet
to its destination due to the limited propagation range of each mobile host’s wireless transmissions.
Routing in a MANET is challenging because of the dynamic topology and the lack of an existing fixed
infrastructure. For this reason, conventional routing protocols are not useful in ad hoc networks. In this
chapter, there is a brief description of the routing protocols in ad hoc networks, which are currently
undergoing a standardization process.
WSNs can be understood as a subset of WMNs. These share similarities with ad hoc wireless networks.
The dominant communication method in both is multi-hop networking, but several important distinctions
can be drawn between the two. These differences result from both the technological structure of
sensor nodes and from the intended application scenarios. Ad hoc networks typically support routing
between any pair of nodes, whereas sensor networks have a more specialized communication pattern
[AY05]; for this reason, new protocols have been designed to be used in WSNs. Three of these protocols are
introduced in this chapter.
WiMAX
tower
INTERNET
WiMAX
tower
WLAN
WLAN
WLAN
WPAN
WLAN
Wireless LAN
WMN (mesh routers)
WMN (mesh clients)
WPAN
(UMTS, GPRS, GSM)
WLAN
WPAN
WLAN
WPAN
FIGURE 4.2
Wireless networks.
© 2011 by Taylor and Francis Group, LLC