Networked Surfaces: A Novel LAN Technology

Networked Surfaces are a novel technology, which allows physical surfaces such as desks to be augmented in order to provide networking and other services to devices placed on top of them. The devices, which are required to be augmented with special hardware, may include notebook PCs, PDAs, peripherals, and other types of device habitually placed on surfaces. When such a device is placed on a Networked Surface, a handshaking protocol is used to establish a connection between it and the appropriate services. These services may include low-speed and high-speed networking, the provision of power, and also the accurate estimation of the location of the device.

The concept of Networked Surfaces raises many issues in networking, which are explored in this thesis in the context of the OSI networking model. At the physical layer, the hardware required to provide connectivity to services is complex, involving a distributed architecture and use of particular conductive pad layouts on the surface and object. The implementation of a fully functional prototype is described. At the link layer, methods for connection and disconnection detection are presented and evaluated. The high speed network used in the prototype is discussed, and includes a novel bus arbitration scheme appropriate to the Networked Surfaces environment. The characteristics of the high speed Networked Surfaces network interface include the possibility of frequent connection and disconnection. This raises issues at the network and transport layers, including those of support for mobility, and of multiple network interfaces. Also discussed are methods of improving the performance of the TCP protocol in these conditions, using a “smart link layer” approach. Finally, the provision and use of location information is presented. The accuracy of this information is found to be comparable with the best current indoor location technologies, with orientation information also provided with a high degree of accuracy. Integration with other systems in the field of “context-aware” computing is described, as well as some applications that Networked Surfaces can enable in this field.