Ubiquitous computing using wireless broadcast

Ubiquitous computing applications collect information from a variety of sources so as to provide behavior that is tailored to the user's context. Typically, client devices connect through appropriate middleware and wireless infrastructure to a variety of services and data sources and, increasingly, local sensor data. In this paper, we present a different approach to constructing ubiquitous computing applications that relies on wireless broadcasting of information by the infrastructure. Clients silently listen to these broadcasts and harvest the data they need. We believe this complementary approach exhibits promising properties for scalability and privacy. All clients receive the same data and use what they need solely by listening and without compromising their presence. We have constructed a broadcast infrastructure in our office building and, together with colleagues, have developed three applications that demonstrate the promise of the approach.