Power Control in Ad Hoc Networks

Abstract

In this chapter, we present the power control techniques used in ad hoc networks. Traditionally, the power control has been implemented and used effectively in cellular networks. While the use of transmission power control in infrastructure based networks has proven to work well and improve performance, the application of power control techniques to ad hoc networks has many challenges and implementation complexities (Chauh & Zhang, 2006) (Basagni et al., 2004). The power control is of great significance in ad hoc networks because of their organizational structure and lack of central management. With the implementation of effective power control techniques, the ad hoc network can improve their vital parameters, such as power consumption, interference distribution, throughput, routing, connectivity, clustering, backbone management, and organization (Basagni et al., 2004). We discuss several power control algorithms commonly used in ad hoc networks to get insight of power control techniques and their effectiveness. Most of the algorithms are adapted from cellular networks, modified accordingly, and proposed for ad hoc networks. Moreover, we argue the enhancement in performance of ad hoc networks with the use of these power control algorithms. The power control requirements vary depending on the physical and network layer implementation of ad hoc networks (Stuber, 2002). We show the application of the prevailing power control algorithms to different physical layer models and discuss their performance. The application to CDMA based networks is emphasized as these types of networks have strict power control requirements and the performance is severely degraded without appropriate power control. In cellular networks, the power control requirements are stringent, especially in multiple access technologies. The appropriate allocation of power to the transmitters facilitates interference control and saves energy. The near-far effect starts to dominate as the transmission power levels are not properly managed. The advantage of cellular networks over ad hoc networks is the presence of central management, and as a consequence, the uplink power control can be achieved. This is in contrast to ad hoc networks, which lack central management and most of the nodes are in peer to peer configuration (Blogh & Hanzo, 2002). In addition, transmit power control is a cross layer design problem affecting all layers of the OSI model from physical layer to transport layer (Jia et al., 2005). In general, power conservative protocols are divided into two main categories: transmitter power control protocols and power management algorithms. Second class can be further divided into MAC layer protocols and network layer protocols (Ilyas, 2003). 22