Cross-layer tuning of the neighbor sensing mechanism in mobile ad hoc networks

The mobility of an ad hoc network can severely degrade the performance of the wireless network, as a direct consequence of frequently occurring link break events. An ad hoc routing protocol must react swiftly to these events by recomputing the forwarding table. Typical routing protocols rely on a timeout mechanism to notify a failing link. This causes a gap between the link failure and the detection of this event, resulting in packet loss for data streams passing over the failing link. In this paper we present a new cross-layer neighbor sensing mechanism for an ad hoc routing protocol in mobile ad hoc networks. By tuning the cross-layer transmission parameters of the neighbor sensing signaling packets, we divide the communication range of the mobile node into two zones: a smaller virtual range for the ad hoc routing protocol and a larger effective communication range for data streams. When a neighboring node moves away, the larger range enables a mobile node to continue to receive data packets from that node, while the routing protocol is reacting to the virtual link break by recomputing the forwarding table. This enables the routing protocol to find an alternative route before the neighboring node moves out of the communication range.