To the best of our knowledge, the idea of simultaneously connecting to multiple wireless networks has not been studied before in the context of wireless LANs. A related problem was considered for scatternet formation in Bluetooth networks in [11,12] among others. Bluetooth networks comprise basic units, called piconets, that can have at most 7 nodes. Piconets are used to form bigger networks, called scatternets, by having some nodes on multiple piconets. However, the problem of enabling nodes in Bluetooth networks to listen to multiple piconets is significantly different from the problem of allowing nodes to connect to multiple IEEE 802.11 networks. Bluetooth uses a frequency hopping scheme for communication between multiple nodes on the network. A node can be on two networks simultaneously if it knows the correct hopping sequence of the two networks and hops fast enough. IEEE 802.11 networks, on the other hand, have no such scheme as we described in Section 3.
The concept of virtualization has been studied in the context of operating systems. VMware [4] uses virtualization to run multiple operating systems on a single computer. Disco [7] is a virtual machine monitor (VMM) that runs multiple operating systems on a scalable multiprocessor and the Denali [15] Isolation kernel uses virtual machines (VMs) to host multiple untrusted services. These systems virtualize all the hardware resources, including the network interface, to form multiple virtual machines. Each virtual machine has its own virtual network interface that it uses for sending and receiving packets.
There are significant differences in the motivation and design of MultiNet and the above virtualization schemes. While VMMs are designed to support multiple operating systems through VMs on a single machine, MultiNet is aimed at supporting multiple networks over one WLAN card. The VMM approach does not work with IEEE 802.11 WLAN cards. VMMs have a bridged architecture in which virtual NICs have MAC addresses that are different from the MAC address of the underlying wireless card. There is no provision for this approach in the IEEE 802.11 standard. Further, different virtual NICs in VMMs may require connectivity to physically different wireless networks. This is currently not possible using existing virtualization schemes.