handled by the physical layer. Wireless nodes also suffer from the hidden and
exposed terminal problems which should be handled by the deployed MAC pro-
tocol. The network layer faces great challenges with the most crucial one the task
of establishing the communication path with its multi-hopping requirements, and
this is the responsibility of the routing sub-layer.
As an essential part of the network layer, routing is a critical element in the
design of networks and networking-based applications. In a multi-hop network, for
a packet to be sent from a source to a destination, it is the responsibility of the
routing protocol to find a path between the two communicating nodes through
intermediate nodes that act as relays for packets. Having multiple intermediate
nodes results in having multiple potential paths to be followed. So, the role of a
multi-hop routing protocol is not only finding a path, but finding the optimal one
that satisfies the needed performance requirements from a set of candidate paths.
Within the paradigm of multi-hop communication, four types of wireless net-
works can be classified as wireless multi-hop networks. These network paradigms
are: Mobile Ad-Hoc Networks (MANETs) [ 1 , 2 ], Wireless Sensor Networks
(WSNs) [ 3 , 4 ], Wireless Mesh Networks (WMNs) [ 5 , 6 ], and Vehicular Ad-Hoc
Networks (VANETs) [ 7 , 8 ]. Being multi-hop networks, these paradigms depend on
a sequence of intermediate nodes for routing packets from a source to a destina-
tion. Although having this feature in common, routing characteristics and func-
tionalities of these four network paradigms have some differences that result in
having different routing protocols uniquely designed for each network paradigm.
These differences emerge from having different characteristics and challenges that
impose requirements on the routing functions for each paradigm. They all utilize
multi-hopping but with different techniques for handling the different routing
The objective of this brief is to highlight the commonalities and distinguishing
features of the aforementioned network paradigms in terms of their routing functions.
The remainder of this brief is organized as follows: in the following sections of this
chapter, we will present a brief introduction to each of the aforementioned network
components that the paradigms have in common. As well, some auxiliary compo-
nents will be discussed. In addition, we will propose a generic routing model that can
be a foundation for the wireless multi-hop routing function and can be inherited by
any wireless multi-hop routing protocol. In Chap. 3 we will shed light on the
distinguishing features of each network paradigm in terms of their design consid-
erations and challenges, and their effects on the routing functions. Furthermore, we
will provide an abstraction of the general routing functionalities for each of the four
network paradigms along with some examples of routing algorithms that adopt these
functionalities. Finally, in Chap. 4 we will present open issues in the area of routing
for wireless multi-hop networks, along with our view of the ideal wireless multi-hop
routing protocol, and some concluding remarks.