Security in Wireless Ad Hoc and Sensor Networks

4

Medium Access and Error Control

To satisfy the broadband service demand in the mobile and error-prone wireless environment, an efficient medium access control (MAC) scheme is required. MAC schemes have significant impact on the system performance, the system capacity and the hardware complexity. A successful MAC scheme needs to take full advantage of the traffic and network characteristics to fulfill the compelling requirements of WASMs.

MAC is considered a part of the data link layer (DLL) in the Open Systems Interconnection (OSI) reference model (Tannenbaum, 2003). The DLL also covers error and flow control on a link basis. Wireless networks introduce additional challenges for flow and error control. Although these challenges are exacerbated by the mobility and self-configuration requirements of ad hoc networks, as well as the stringent resource and energy constraints of WASMs, error control schemes developed for wireless networks in particular may also be applicable to many WASM applications.

4.1 Medium Access Control

MAC schemes for wireless networks have been extensively studied and numerous MA protocols have been proposed in the literature. In this chapter, we first classify the MA schemes with an holistic approach and examine those commonly used in wireless and tethered networks. Then we explain MAC protocols specifically designed for WASMs.

4.1.1 Generic MAC Protocols

MAC protocols can be broadly categorized into three classes: contention-based, conflict-free and hybrid ...