Today, when ad hoc networking professionals or would-be professional talk about ad hoc networks, they almost always implicitly assume that these networks are based on one of the wireless local area network (WLAN) technologies. The majority of research papers published on simulation-based performance evaluation of proposed ad hoc routing protocols assume underlying WLAN medium access control (MAC) and physical (PHY) layers. Most recently, with the appearance of short-range wireless personal area

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... networking (WPAN) technologies, researchers also started to use the characteristics of these technologies as a basis for underlying transport assumptions to evaluate their novel network (or higher-) layer protocols. It is extremely important to point out, that WLANs and WPANs are significantly different from ad hoc networks. Ad hoc networks have received their name due to the fact that there is no predefined structure or infrastructure of communication over which they should be established, but they consist of nodes that relay information to their neighbors possibly on behalf of other neighbors. Ad hoc networks are often called wireless multihop networks due to the fact that most packets will have to be relayed by several nodes before they reach their destinations. WLANs, on the other hand, are based on infrastructure-just like cellular networks-where there are dedicated access points (likely connected to the wired infrastructure) controlling their entire transmission range, namely their wireless domain. WLANs are considered single-hop networks, since all nodes attached to the access point talk to only the access point, which is the only entity equipped with a routing function. Fortunately, as outlined in the next subsection, the histories and requirements for ad hoc and Ad Hoc Networking. Edited by Basagni, Conti, Giordano, and Stojmenovic. 47