We develop an anycast mechanism at the link layer for wireless ad hoc networks. The goal is to exploit path diversity in the link layer by choosing the best next hop to forward packets when multiple next hop choices are available. Such choices can come from a multipath routing protocol, for example. This technique can reduce transmission retries and packet drop probabilities in the face of channel fading. We develop an anycast extension of the IEEE 802.11 MAC layer based on this idea. We implement the protocol in an experimental proof-of-concept testbed using the Berkeley motes platform and S-MAC protocol stack. We also implement it in the popular ns-2 simulator and experiment with the AOMDV multipath routing protocol and Ricean fading channels. We show that anycast performs significantly better than 802.11 in terms of packet delivery, particularly when the path length is large or fading is substantial.

The principles of Anycast may be applied in multichannel and directional antenna MAC protocols to alleviate problems like deafness and hidden terminals. We have evaluated Anycast in multichannel and directional antenna networks.

Shweta Jain and Samir R. Das, “Exploiting Path Diversity in the Link Layer in Wireless Ad Hoc Networks,” In Proc. of the 6th IEEE WoWMoM Symposium, Taormina, Italy, June 2005 jains_pathdiversity.pdf wowmom.ppt

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• M. Takai, J. Martin, R. Bagrodia, and A. Ren. Directional Virtual Carrier Sensing for directional antennas in mobile ad hoc networks. In ACM Mobihoc, pages 39–46, June 2002.

• Faculty: Samir R. Das
• Graduate Student: Shweta Jain

Please send all questions and comments to Shweta Jain at email.