WIRELESS COMMUNICATIONS AND MOBILE COMPUTING Wirel. Commun. Mob. Comput. (2011) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/wcm.1181 RESEARCH ARTICLE A Generic Polymorphic Unicast Routing Protocol for vehicular ad hoc networks Adel Ben Mnaouer 1 * , Chuan Heng Foh 2 and Lei Chen 2 1 College of Computer Engineering and Information Technology,Dar Al-Uloom University, Riyadh, Saudi Arabia 2 School of Computer Engineering,Nanyang Technological University, Singapore ABSTRACT In this work, we present a new generic polymorphic routing protocol tailored for vehicular ad hoc networks (VANETs). Similar to the case of mobile ad hoc networks, the routing task in VANETs comes under various constraints that can be environmental, operational, or performance based. The proposed Polymorphic Unicast Routing Protocol (PURP) uses the concept of polymorphic routing as a means to describe dynamic, multi-behavioral, multi-stimuli, adaptive, and hybrid routing, that is applicable in various contexts, which empowers the protocol with great flexibility in coping with the timely requirements of the routing tasks. Polymorphic routing protocols, in general, are equipped with multi-operational modes (e.g., grades of proactive, reactive, and semi-proactive), and they are expected to tune in to the right mode of operation depending on the current conditions (e.g., battery residue, vicinity density, traffic intensity, mobility level of the mobile node, and other user-defined conditions). The objective is commonly maximizing and/or improving certain metrics such as maximizing battery life, reducing communication delays, improving deliverability, and so on. We give a detailed descrip- tion and analysis of the PURP protocol. Through comparative simulations, we show its superiority in performance to its peers and demonstrate its suitability for routing in VANETs. Copyright © 2011 John Wiley & Sons, Ltd. KEYWORDS vehicular ad hoc network; routing protocols; polymorphic routing *Correspondence Adel Ben Mnaouer, College of Computer Engineering and Information Technology,Dar Al-Uloom University, PO Box 3535, Riyadh 13314-7222, Saudi Arabia. E-mail: adelm@dau.edu.sa 1. INTRODUCTION Mobile ad hoc networks (MANETs) and vehicular ad hoc networks (VANETs) are two representative types of dynamic networks (DNs). Although a unified definition of DNs is not obvious, we do characterize them as fol- lows: they are networks subject to frequent changes in their structural (i.e., topological) or functional (i.e., behavioral) characteristics, which may be based on hybrid architec- tures that are supposed to cope with different classes of traffic or provide various classes of services. Vehicular ad hoc networks represent a special type of MANETs where mobile nodes (MNs) are mounted on vehicles and are characterized by more regular mobility patterns (following roads and traffic rules and conditions) and by irregular and fluctuating speed levels. Some of the main hurdles in the deployment of efficient routing protocols for MANETs are the randomness of the mobility patterns of MNs and their limited battery supplies. Another issue of concern is the wastage of signal power when a single transmission rate is used. However, with VANETs considered, these two hurdles are almost elim- inated as the mobility patterns of MNs are more or less predictable, and the power supply is no longer a problem as an MN draws power directly from the vehicle host- ing it. Consequently, routing protocols for VANETs should be designed with no concerns for power supply but with specific constructs that should potentially benefit from the regularity of the mobility patterns. Nevertheless, VANETs have their own specificities that relate to the fact that routing paths may experience high level of breakages during high-speed node mobility. As such, a trend in routing protocol design has focused on enhancing them with delay/disruption tolerance mecha- nisms and with opportunistic routing features [1–3]. Furthermore, as a further refinement of the design of routing protocols that are suited for DNs, a new paradigm known as polymorphic behavior-based routing Copyright © 2011 John Wiley & Sons, Ltd.