Bay Area Research Wireless Access Network (BARWAN)
Wireless Overlay Subnet Layer
This corresponds to the physical, data link, and network layers in the
OSI terminology. It represents the independent wireless networks to be
integrated by the proposed overlay architecture. These networks will
interface to the rest of the architecture through the standard Internet
IP protocol suite. In general, the details of the underlying physical
channels, media access protocols, link-level protocols, and routing
protocols are not visible above this layer, because these will be
provided by a commercial network service provider, our so-called
"black pipe" networks. There is no way for us to take advantage
of them at the next level up, the Overlay Network Management Layer.
However, for in-building RF and IR networks, we have the ability to fully
expose the underlying protocols, including those that control handoff
decisions.
For example, IR provides advantageous cell confinement, finer location
tracking, better spectrum reuse, and higher aggregate bandwidth with the
potential for higher raw bandwidth (50 Mbps IR devices have been demonstrated).
IR is particularly well suited for confined spaces, like offices and meeting
rooms, that are smaller than 30 m by 30 m. However, handoff between IR cells
is not easily accomplished, especially when crossing into large open spaces
like corridors. An RF overlay advantageously provides connectivity for these
gaps in IR coverage, as well as providing an alternative source of bandwidth
for areas of heavy traffic. We plan on exploiting exposed information, such
as the degree to which network resources are already allocated to mobile hosts,
to demonstrate the capabilities of cooperative management of overlay networks.
Randy H. Katz, ed., randy@cs.Berkeley.edu; Last edited: 22 APR 95