Higher-layer issues: Ad hoc and sensor networks
Maria‐Gabriella Di Benedetto, Luca De Nardis, Salvatore Esposito De Falco · 2006
Ultra-wide-band (UWB) radio has the potential of allowing simultaneous communication of a large number of users at high bit rates [1–3]. In addition, the high temporal resolution inherent to UWB provides robustness against multipath fading and is particularly attractive for indoor local area network (LAN) applications. UWB is also capable of recovering distance information with great precision. As we will show later in this chapter, distance and position data can lead to better organization of wireless networks, for instance, through better resource management and routing [4]. UWB signals spread, however, over very large bandwidths and overlap with narrowband services. As a consequence, regulatory bodies impose severe limitations on UWB power density in order to avoid interference provoked byUWBonto coexisting narrowband systems [5]. It is therefore necessary to take into account power considerations when designing UWB systems. Throughout this chapter we will show how the distance information made available by the UWB technology can be exploited to achieve low power levels and increase network lifetime in the long term, while providing an adequate network performance (in terms of data throughput) in the short term. In the last few years, the increasing interest in applications based on the deployment of ad hoc networks triggered significant research efforts regarding the introduction of the energy-awareness concept in the design of medium access control (MAC) and routing protocols. Ad hoc networks are in fact considered as a viable solution for scenarios in which fixed infrastructure, and consequently unlimited power sources, are not available. In such scenarios, an efficient management of the limited power supply available in each terminal is a key element for achieving acceptable network lifetimes. This is particularly true for sensor networks, for which long battery duration is one of the basic requirements, given the typical size of such networks (up to thousands of terminals), as will be analyzed in Section 4.2. Location information is another valuable way of achieving energy-awareness in ad hoc networks. In Section 4.3 we first review location-aware routing protocols