Distributing identity [symmetry breaking distributed access protocols]

In the next few years, computational, sensory, and communication capabilities will diffuse out of their present home in beige boxes on desktops and into everyday objects such as furniture, clothing, and other non-technological objects. As the cost of electronics continues to drop, the number of activated, networked devices will grow rapidly. Each device sharing a particular multiaccess channel will need a unique identifier for that channel. Present communication protocols such as Ethernet specify that the manufacturers must coordinate with one another in order to avoid assigning the same ID twice. The article explores methods by which the devices could coordinate with one another to manage ID assignment dynamically and automatically. In particular, the article is an investigation of distributed protocols that utilize physical sources of symmetry breaking to enable a network of initially identical units to acquire the unique identities required for point-to-point communication over a shared resource such as a bus or common RF band. It presents several protocols, compares their resource use (time, random bits, space, communication), and notes a trade-off among these measures of algorithm complexity