When 802.11 developers talked of "ad hoc networks" in the late 1990s, they speculated about flexible, self-organizing networks, in which an individual user node would join and leave as appropriate tasks were initiated or completed.
When 802.11 developers talked of "ad hoc networks" in the late 1990s, they speculated about flexible, self-organizing networks, in which an individual user node would join and leave as appropriate tasks were initiated or completed. The security concerns inherent in such membership self-selection, and the overall difficulty of managing WLAN mesh networks, made these grand visions recede into the distant future.
But a tour this month of wireless research facilities in Scotland gave me the impression that work on ad hoc membership is progressing, allowing a hierarchical and flexible use of PANs, LANs and 3G in a seamless network. The multi-university Speckle computing project upgrades the RF sensor network concept with better-distributed intelligence per node and breaks new ground in node processing.
Another element of such re-search is the Digital Marketplace project at the University of Strathclyde in Glasgow. There are many ideas for managing personal digital environments through a topology where all services are based on Internet Protocol, using multihop routing methods that can even include digital broadcast. Where the Strathclyde work differs is in defining localized info stations as "radio caches" to cut the cost of information distribution.
The Digital Marketplace network also defines a device-management entity (DME), which takes control of setting up local clusters of information processing at a level of granularity most appropriate for the user in an automotive PAN, an enterprise LAN, even a cluster of computing nodes on a user's body.
The whole notion of "device" changes in such a topology, as does the local network. An end node might be one handset or PDA, but it might equally be a cluster of distributed computers connected via Zigbee or Bluetooth. The extremely local cluster might look like a LAN in a larger granularity, and the cluster could elect to join an enterprise LAN. This larger LAN then might appear as a device to a global WAN, with DMEs controlling access at each hierarchical level.
A service provider could offer a wealth of interesting services under such a flexible network, said EE professor John Dunlop. Location knowledge of the user could be proxy-based or Session Initiation Protocol-based, and several DMEs could refer to a home-based "root DME."
Dunlop said the real power of multiple ad hoc nets resides in "opportunistic communication," where a foreign network interrogates a local device to learn compatibility and capability, and adjusts itself to the local environment. Maybe ad hoc concepts have a long way to go, but it feels as though adaptive-network membership concepts are getting somewhere.
Loring Wirbel is Communications editorial director for EE Times and its network publications.