Seamless Client Mobility support in Wireless Mesh Networks

In this project we designed iMesh, a wireless mesh network architecture for community networking applications that can provide seamless networking services to the mobiles both for last mile access and peer-to-peer access. The iMesh architecture uses 802.11-based access points (AP) that also double as mesh backbone routers. The fundamental design goal that we pursue is client side transparency. The mobile stations are unaware of the mesh networking backbone and they view the network as a conventional wireless LAN spread out over an extended geographic area. Thus the clients still associate with an AP using a traditional association mechanism in wireless LANs. When the client moves and re-associates with a different AP, a layer-2 handoff event occurs that in turn triggers appropriate routing updates in the mesh network backbone. Thus, the handoff process involves both layer-2 and layer-3 procedures. We describe how the layer-2 and layer-3 handoffs work together efficiently, and present design choices for the layer-3 handoff process – one using a mobile IP like solution called Transparent Mobile IP and the other using a “Flat” routing protocol. We also present a detailed performance evaluation of the handoff latencies in both layers. The performance results demonstrate excellent handoff performance with an average layer-3 handoff latency of 10ms. Various performance measurements also demonstrate the clear superiority of a flat routing scheme relative to a more traditional, mobile IP-like scheme to handle layer-3 handoff. Overall, the iMesh architecture demonstrates the feasibility of supporting seamless mobility in a wireless mesh network even in presence of frequent handoffs.

Vishnu Navda

Anand Kashyap

Samir Das

Samrat Ganguly

• Performance Optimizations for Deploying VoIP Services in Mesh Networks - Samrat Ganguly, Vishnu Navda, Kyungtae Kim, Anand Kashyap, Dragos Niculescu, Rauf Izmailov Sangjin Hong and Samir Das. IEEE Journal on Selected Areas in Communications(JSAC) Multi-hop Wireless Mesh Networks, 4th Quarter 2006. PDF

• Design and Evaluation of iMesh: an Infrastructure-mode Wireless Mesh Network - Vishnu Navda, Anand Kashyap and Samir Das. IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks (WOWMOM), Italy, June 2005. PDF. Extended version appears as a book chapter in Marco Conti, Jon Crowcroft, Andrea Passarella (Editors): Multi-hop Ad hoc Networks from Theory to Reality, Nova Science Publisher, 2007 - 2nd Quarter, ISBN: 1-60021-605-6

• Design of a multi-hop wireless LAN - Vishnu Navda, Salil Gokhale, Anand Kashyap, Samir Das. Demo & Poster ACM Mobisys Poster/Demo Publicity Session, Boston, June 2004 Poster Abstract

• Stony Brook Mesh Router: Architecting Multi-Radio, Multihop Wireless LANs - Samir Das, Vishnu Navda, Mahesh Marina and Anand Kashyap. Talk at Microsoft Research Mesh Networking Summit, June 2004. PPT