12.1. Introduction

Recent trends indicate that the next-generation wireless networks will consist of hybrid wireless access networks and wireless sensor networks (WSNs) [1–3]. The wireless access networks will be hybrid, i.e., they will consist of wide-area mobile data services providing extensive coverage but lower data rates and wireless local area networks (WLANs) for covering local area hot spots with much higher data rates [2]. Wireless ad hoc connections can assist with missing connections between a wireless device and the rest of a network [1, 3]. WSNs are becoming increasingly relevant for sensing physical phenomenon for a variety of applications (e.g., structural health monitoring, sampling soil quality). All of these wireless networks are expected to be interconnected in the future.

Already, the public’s demand for and dependence on mobile services makes existing wireless networks a part of the nation’s critical network infrastructure (CNI), and ongoing development of next-generation wireless networks only increases their importance. The continually increasing reliance on wireless networks by businesses, the general public, and government services, and their role in the CNI of the country make it imperative to have information assurance (IA) built into them. IA for wireless networks is an emerging research area with relatively little literature in comparison to wired networks. While individual wireless technologies currently incorporate some in-built security features, these have been implemented in a largely uncoordinated manner. Availability features for wireless systems are either nonexistent or not well understood [4]. Moreover, IA techniques employed in wired networks have limited direct applicability in wireless networks because of the unique aspects of wireless networks (e.g., user mobility, wireless communication channel, power conservation, limited computational power in mobile nodes, security at the link layer). IA in WSNs is unique in that the faults and threats that need to be considered are quite different from those in other kinds of networks or distributed systems. Sensor networks consist of perhaps thousands of low-cost, battery-operated units with limited computational power and memory that need to communicate potentially with one another and some sink or base station using wireless links. Consequently, scalability (because of the sheer numbers of nodes), energy efficiency, necessity of lightweight cryptographic protocols, and methods to overcome wireless vulnerabilities are important. Also, it is not possible to assume that sensor units will not be compromised or tampered with for the same reasons. Hence, it is important to consider both outsider and insider threats in sensor networks. Low-cost sensor nodes are likely to fail randomly or stop working due to limited battery life.