Fast and Accurate Link Discovery Integrated with Reliable Multicast in 802.11

Maintaining accurate neighbor information in wireless networks is an important operation upon which many higher layer protocols rely. However, this operation is not supported in the IEEE 802.11 MAC layer, forcing applications that need it to each include their own neighborhood mechanism, creating redundancies and inefficiencies and failing to capitalize on potential synergies with other MAC layer operations. In this work, we propose to integrate link discovery and neighborhood maintenance with a reliable multicast extension to the IEEE 802.11 MAC. We show through simulations that our protocol adapts to neighborhood changes faster than traditional neighborhood maintenance mechanisms, thereby allowing MAC-layer multicast operations to achieve higher delivery rates. We also demonstrate that our protocol can quickly and reliably distinguish between unidirectional and bidirectional links. Traditional mechanisms assume links are bidirectional based on one-way reception of a short “hello” packet, which results in significant problems with higher-layer operations such as routing because of many unidirectional links being classified as bidirectional.