A VIRTUALIZATION ARCHITECTURE FOR WIRELESS NETWORK CARDS

This doctoral dissertation describes the design and applications of a new virtualization architecture for wireless network cards, called MultiNet. MultiNet virtualizes a sin-gle wireless card to appear as multiple virtual wireless cards to the user. Each virtual card can then be configured separately on a physically different network. The goal of MultiNet is to provide a user-level illusion of simultaneous connectivity on all virtual cards although the network card is on a single network at any instant. MultiNet achieves this transparency using intelligent buffering and switching algorithms. The switching and buffering mechanisms are implemented as a kernel driver, while the policies are implemented as a user-level service. The MultiNet system has been implemented over Windows XP and has been operational for over two years. It is agnostic of the upper layer protocols, and works well over popular IEEE 802.11 wireless LAN cards. Further, MultiNet enables a new class of applications, which were earlier only possible with multiple wireless cards in the device. This dissertation describes two such applications: Slotted Seeded Channel Hopping (SSCH) and Client Conduit. SSCH is a new channel hopping protocol that works over MultiNet, and utilizes fre