**1. Introduction**

Wireless Mesh Networks (*WMNs*) and Mobile Ad-Hoc Networks (*MANETs*) are applied in situations where there is no predefined network structure consisting of routers and base station or where the network is dynamic due to a growing number of nodes or mobile nodes moving into areas that have not been previously covered by a base station. Examples for such networks are Wireless Sensor Networks (*WSNs*) [1], vehicle ad-hoc networks [2], Wireless Senthe OLPC mesh network for children's computer in developing countries [3], and open grassroots initiatives to support free computer networks such as the Freifunk initiative in Germany [4] or the Funkfeuer initiative in Austria [5].

Routing of messages is a major challenge in such networks due to the dynamic or not *a priori* known network structure. Besides the problem of finding an optimum (or acceptable route) for a message, there is also a mutual influence of a used route on other routes. This calls for a self-organizing approach [6] of choosing routes that are near-optimal on a global level with a decision based on local information.

Artificial ant algorithms give a promising approach for such algorithms. Artificial ant algorithms are bio-inspired algorithms based on real ants' foraging behavior using a local gradient-following search strategy with pheromone trails. There are different ways how an ant-inspired algorithm can be implemented in Wireless Multi-Hop Networks, for example, by representing ants via network packets and

the pheromone by values assigned to the network nodes. Besides the mapping of biological properties into a computer network, Algorithms differ in how route discovery and maintenance are implemented. This chapter investigates different ant algorithms and discusses their applicability to routing in wireless multi-hop networks.

The following section gives an introduction to ant-inspired emergence and selforganization. In Section 2, three forms of Wireless Multi-Hop Networks are introduced (*MANET*, *WSN*, or *WMN*). Section 3 describes first the seminal ant routing algorithm developed for routing in such networks, *AntHocNet*, followed by an overview of algorithms which build upon this algorithm. Section 4 provides a summary and concluding remarks.
