Connecting to Multiple
Networks using a Single Radio
Victor Bahl and Pradeep
Bahl
Applications
Some Solutions
Design
Constraints
§ Power:
Independent power consumption by multiple wireless cards results in drastic reduction of battery
life.
=> Use a single radio, but problems
of
§MAC:
Wireless card can be associated to at most one wireless network.
§Firmware:
Wireless cards send packets only after association to a network.
Switch the radio across multiple wireless
networks. Send packets when the network is active,
otherwise buffer. Buffered packets are sent when the network gets activated.
MultiNet Approach
§Transparency:
Switching across
networks should be transparent to
the user.
§Scalability:
The proposed solution
should scale with the number of
users in the network.
§Backward Compatibility:
The solution should
work with legacy wireless cards.
Design Principles
Buffering
• Use Multiple Radios:
Have one
radio for each desired network.
• Use a single radio
Software approach to stay connected to multiple networks with a single radio.
Problem:
Handle packets whose destination has switched to another network using MultiNet. Packets are lost if not unhandled
Solution:
Buffer packets using PSM at APs for IS networks, and end hosts for AH networks.
Ranveer Chandra
Cisco Guy at
Microsoft
Microsoft
Employee
Microsoft
Employee
Ad Hoc
Infrastructure
Many more applications, such as:
• Gateway node of
a wireless ad hoc network
• Bluetooth
scatternets
• Extending the
range of an infrastructure network
MultiNet is
implemented as a combination of NDIS IM driver and a user level service
Driver:
§ MMD: Miniport instances. One per network, and
IP sees each MMD as a
different network card.
§ MPD: Manages MMDs, switches card and buffers packets.
Service:
§ Maintains
synchronization with other MultiNet nodes
§ Sends signals to
the IM driver using IOCTLs.
Screen Snapshot
Switching
Strategies
Switching strategies are
application dependent.
Power (MultiNet
vs Dual Radio)
MultiNet
consumes around half the total power consumed by the two radio approach for two networks.
