Connecting to multiple IEEE 802.11 networks with
one WiFi card
VirtualWiFi is a virtualization architecture
for wireless LAN (WLAN) cards. It abstracts a single WLAN card to appear as
multiple virtual WLAN cards to the user. The user can then configure each
virtual card to connect to a different wireless network. Therefore, VirtualWiFi
allows a user to simultaneously connect his machine to multiple wireless
networks using just one WLAN card. This new functionality introduced by
VirtualWiFi enables many new applications, which were not possible earlier
using a single WLAN card. For example,
In more recent work, we have explored two more applications of VirtualWiFi. The
first application, which is a very useful tool for fault diagnosis and recovery
in infrastructure wireless networks, is called Client Conduit.
Client Conduit is a tool that provides a thin pipe of communication between
disconnected clients and back end servers that perform wireless diagnosis and
recovery. The thin pipe is achieved by running VirtualWiFi on the connected
clients. These clients dynamically connect to disconnected clients over an ad
hoc network, and send messages from them to the back end servers. VirtualWiFi
enables this thin pipe without requiring the connected client to explicitly
disconnect from the infrastructure network. A more detailed description of
Client Conduit can be found in the paper titled: "Architecture
and Techniques for Diagnosing Faults in IEEE 802.11 Infrastructure Networks".
The second application of VirtualWiFi that increases the capacity of wireless
ad hoc networks using orthogonal channels is called Slotted
Seeded Channel Hopping (SSCH). SSCH uses VirtualWiFi to
virtualize a wireless card with as many instances as the number of orthogonal
channels. It then connects each virtual wireless card on a different orthogonal
channel. Furthermore, SSCH proposes a novel scheme of partial synchronization
that can be used with VirtualWiFi. The details of the SSCH protocol are
described in another paper, titled: "SSCH: Slotted
Seeded Channel Hopping for Capacity Improvement in IEEE 802.11 Ad-Hoc Wireless
Networks".
We have implemented VirtualWiFi over Windows XP. The current version is a
prototype implementation of VirtualWiFi, and we are in the process of making
our software more robust to include more features. Your comments are very
welcome.
Learn more about VirtualWiFi by clicking on the following links:
VirtualWiFi has been used in two projects by the
Networking Group at Microsoft Research. More details about these projects can be found on
the following websites:
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