Abstract: Packets are processed (e.g., routed or classified) in accordance with a braided trie, which represents the combination of two or more different original tries (e.g., representing different forwarding/classification tables). The different tries are combined by twisting the mappings for specific trie nodes to make the shapes of the different tries more similar. Each node in the braided trie contains a braiding bit for at least one original trie indicating the mapping for that trie's node. Trie braiding can significantly reduce the number of nodes used to represent the different original tries, thereby reducing memory usage and improving scalability. Braided tries can be used for such applications as virtual routers and packet classification in which different forwarding/classification tables are represented by a single braided trie stored in shared memory.

Abstract: The set T of all categories in a population of RFID tags is estimated within a specified error bound. For each of one or more frames, a reader broadcasts a probability p, a multiplicity d, a frame size M, and a seed value R to the present tags. A deterministic algorithm on each tag, and known to the reader, calculates (i) whether the tag will transmit in this frame, and, if so, (ii) in which slots the tag will transmit a single “1.” When the tags have responded, the reader calculates set T by initially assuming that all possible categories are in set T and then eliminating those categories that would have transmitted in those slots in which no tag transmitted. Alternatively, the reader initially assumes that set T is empty, and adds those categories that would have transmitted in those slots in which one or more tags did transmit.