If a mobile computing device knows how it is positioned and oriented in relation to other devices nearby, then it can provide enhanced support for multi-device and multi-user interactions. Existing systems that provide position information to mobile computers are reliant on externally deployed infrastructure, such as beacons or sensors in the environment. We introduce the Relate system, which provides fine-grained relative position information to co-located devices on the basis of peer-topeer sensing, thus overcoming dependence on any external infrastructure. The system is realised as a hardware /software plug-in, using ultrasound for peer-to-peer sensing, USB to interface with standard mobile devices, and data abstraction and inferencing to map sensor data to a spatial model that maintains both quantitative and qualitative relationships. We present a set of services and applications to demonstrate the utility of the system. We report experimental results on the accuracy of the relative position and orientation estimates, and other aspects of system performance.

If a mobile computer knows how it is positioned and oriented in relation to other mobile devices nearby, then it can provide enhanced support for multi-device and multi-user interactions. Existing systems that provide position information to mobile computers are reliant on externally deployed infrastructure, such as beacons or sensors in the environment. We introduce a novel system, Relate, which provides fine-grained relative position information to co-located devices on the basis of peer-to-peer sensing, thus overcoming dependence on any external infrastructure. The system is realized as hardware/software plug-in, using ultrasonic devices for peer-to-peer sensing, USB to interface with standard mobile devices, and data abstraction and inference to map sensor data to a spatial model that maintains both quantitative and qualitative relationships. We present a set of services and applications to demonstrate the utility of the system and report experimental results on system performance.

Knowledge of the fine-grained location and orientation of devices on a surface can be used to enhance the surface-based computing tasks of mobile users in the home and workplace. However, existing systems which provide surface-based positioning information are often not a practical solution for mobile users, since the systems all rely upon pre-installed and calibrated environmental infrastructure. In this paper, we present prototype positioning devices for surfaces which do not rely on such infrastructure. We show that inexpensive infrared transducers can be used to effectively sense relative location and orientation of surface devices. We evaluate the novel approach of using intensity of light pulses for fine-grained location measurements.