Connecting to multiple
IEEE 802.11 networks with one WiFi card
(VirtualWiFi is an old
project, and we started working on it in 2002. We are not actively working on
this project since 2006, and will not be supporting this software at Microsoft
Research. Thanks for your interest. However, the software and code will still
be available for you to play around with. Also, check out the supported
VirtualWiFi OIDs in Windows 7.)
VirtualWiFi (previously known as MultiNet) 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,
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With VirtualWiFi, you
can connect to a guest's machine or play games over an ad hoc network, while
surfing the web via an infrastructure network.
·
You can use VirtualWiFi
to connect your ad hoc network, which may contain many nodes, to the Internet
using only one node.
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VirtualWiFi can help
make your home infrastructure network elastic by extending its access to
nodes that are out of range of your home WiFi Access Point.
We have explored several
other applications of VirtualWiFi. The first application is called Client Conduit, which is a very useful tool for fault
diagnosis and recovery in Wireless LANs. Client Conduit is a tool that provides
a thin pipe of communication for disconnected clients to exchange diagnosis
information with the back end servers. 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".
The third application of VirtualWiFi is called WiFiProfiler, which enables clients to cooperatively diagnose the root cause
of various wireless problems. Clients, including the ones that are disconnected
from the WLAN, use VirtualWiFi to form an information plane, which is different
from the data plane (the WLAN). All clients then exchange configuration
information over this information plane and use this information to diagnose
the root cause of various wireless failures. The details of this idea are
described in a technical paper, titled: "WiFiProfiler:
Cooperative Diagnosis in Wireless LANs".
We have implemented VirtualWiFi on 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:
·
Frequently
Asked Questions about VirtualWiFi
·
VirtualWiFi
Software: Download and Usage Instructions
(Downloaded more than
100,000 times from this website. Also distributed to more than 400 universities
worldwide as part of the Mesh Academic
Resource Toolkit.)
·
VirtualWiFi
Documents: Papers and Talks
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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