Microsoft Tests 'Virtual Wi-Fi' Software http://www.eweek.com/print_article2/0,1217,a=163185,00.asp October 20, 2005 By Chris Preimesberger Researchers at Microsoft Corp. have created the prototype for new Wi-Fi software that allows a user on a PC with a single network card to connect to multiple local area networks concurrently via "virtual mirrors." Wi-Fi?short for wireless fidelity?is meant to be used generically when referring of any type of 802.11 network, whether 802.11b, 802.11g, dual-band, etc. The term is promulgated by the Wi-Fi Alliance "VirtualWiFi is a virtualization architecture for wireless LAN [WLAN] cards," lead researcher Ranveer Chandra told Ziff Davis Internet. "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." This new functionality enables many new applications that were not possible earlier using a single WLAN card, Chandra said. For example, this new development would open new options for employees within an enterprise who need to do work outside the company network, he said. A person using VirtualWiFi and connected to two or more networks at the same time becomes, in effect, a "router" for those networks?obtaining, strengthening and passing on the bandwidth to others in the immediate area, Chandra said. "We're still studying the implications of this," he told Ziff Davis Internet. Chandra and his team have implemented VirtualWiFi to run on Microsoft Windows XP systems only at this time. It is available for free download and evaluation here. http://research.microsoft.com/netres/projects/virtualwifi/software.htm Chandra offered other examples of how this virtualization software works. For example: 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. 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. "In more recent work, we have explored two more applications of VirtualWiFi," he wrote on his Web site. "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, Chandra said. 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, Chandra said. 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 written by Chandra and three colleagues, "Architecture and Techniques for Diagnosing Faults in IEEE 802.11 Infrastructure Networks," here in PDF form. The second application of VirtualWiFi that increases the capacity of wireless ad hoc networks using orthogonal channels is called SSCH (Slotted Seeded Channel Hopping). 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, Chandra wrote on his Web site. "We are in the process of making our software more robust to include more features. [Testers'] comments are very welcome," Chandra said. Chandra said he did not know exactly how his employer, Microsoft, plans on utilizing the software in the future. "There are a lot of possibilities," he said. Chandra has been working on this technology for about two years, he said, since he started the project at the Department of Computer Science at Cornell University. Chandra joined Microsoft Research in Redmond, Wash., about two months ago, he said. Check out eWEEK.com's Mobile & Wireless Center for the latest news, reviews and analysis on mobile and wireless computing. Copyright (c) 2005 Ziff Davis Media Inc. All Rights Reserved.