802.11s extends wireless outdoors

Access points interconnected with peer-to-peer wireless links create a backhaul infrastructure called a wireless mesh network. These networks extend service across large geographic areas, such as campuses or metropolitan areas, facilitating expanded broadband wireless applications.

An IEEE technical group is working to develop the 802.11s standard for wireless LAN (WLAN) mesh networking. At last month's plenary session, the group announced the baseline document for the standard. The group expects to have an initial draft by July and a ratified 802.11s standard by early 2008.

The group is defining capabilities in several areas, including:

•  Topology discovery.

•  Path selection and forwarding.

•  Channel allocation.

•  Security.

•  Traffic management.

•  Network management.

Mesh networks introduce some new terminology. The mesh architecture defines a mesh point as a node that supports mesh services. A mesh point that supports access-point services as well as mesh services is called a mesh access point. A variant of a mesh point that connects into the wired network is called a mesh portal.

The existing 802.11 media access-control layer is being enhanced to support mesh services. Mesh networking will work with existing 802.11 radio technologies. Mesh services will be compatible with existing WLAN clients.

In a mesh network a mesh node must be able to discover its peers and associate with them. A node should also be able to select an optimal path through a mesh network to forward data frames. The standards group is working on a path-selection protocol called Hybrid Wireless Mesh. The specification is being designed in such a way that vendors can use their own protocols for path selection, so interoperable and proprietary mesh deployments will be possible.