Multihop Wireless Networks: Opportunistic Routing

9.1 Attack on Link Quality Measurement

The packet reception ratio (PRR) has been widely used as an indicator of the link reliability in multihop wireless networks. It has been shown that routing performance is significantly improved by considering the link PRR information. For example, expected transmission count (ETX)-based routing achieves much higher throughput than traditional minimum-hop routing protocols in wireless mesh networks (Couto et al. 2003). The ETX is defined as , where pf and pr is the forward and reverse link PRR, respectively. Recent work in sensor networks (Sang et al. 2007) suggests a link metric (ETF), expected number of transmissions over forward links, which only considers forward link PRR. State-of-the-art geographic routing protocols (Seada et al. 2004; Zeng et al. 2007b) and most opportunistic routing protocols (Biswas and Morris 2005; Zeng et al. 2007a) rely on link quality information to make routing decisions.

Providing accurate link quality measurement (LQM)1 is essential to ensure the correct operation of the above protocols/schemes. Furthermore, LQM is also important in supporting QoS guarantees in multihop wireless networks. Lastly, accurate long-term statistics about link-quality information are necessary to diagnose a network to identify the source of network failures and reduce the management overhead.

The existing LQM mechanisms proposed in the ...