1.4 Wireless Mesh Networks
Wireless Mesh Networks (WMNs) were proposed as an efficient technology to
provide broadband access to users not in the direct coverage of wired access points
by extending the backhaul access using wireless communications. Isolated Local
Area Networks (LANs) can be connected together and coverage can be extended
without incurring the cost and inconvenience of deploying a wired infrastructure.
A WMN is comprised of three tiers of networking components: (1) the mesh
clients which are the user devices seeking access to the broadband network, (2) the
wireless mesh routers (WMRs) that provide connectivity to the mesh clients and
are connected together in a multi-hop fashion for covering the access area, and
(3) the gateways which are connected to the mesh routers and provide the last mile
access to the Internet. The general architecture is illustrated in Fig. 1.3 . Only
gateways need wired connection to the backhaul network. Being deployed in an
ad-hoc fashion, wireless routers can be incrementally added to the network for
further extension of the covered area as needed [ 5 ]. Except for the intra-mesh links
which should be wireless, all other links can be either wired or wireless [ 12 ].
Clients can connect to the WMRs using any common network interface (e.g.,
802.11, Ethernet, Bluetooth). WMRs can have multiple radio interfaces and can
support multi-channel operation.
The extended coverage capabilities provided by WMNs motivates a promising
market and applications. The main objective for designing WMNs was to provide
public Internet access for areas not covered by wired infrastructure. In addition to
its main objective, WMNs can support other applications: communications for
ITS, public safety, broadband home networking, community and neighbourhood
networking, enterprise networking and building automation [ 5 ].
Communication in WMNs can be in one of two patterns: communication
between a mesh client and a gateway for the broadband access, or communication
Mesh Router / Gateway
Backhaul Wired Link
Intra-mesh Wireless Link
Wireless Access Link
Wired Access Link
Architecture and components of a wireless mesh network