Efficient, reservation-based CSMA/CD protocols for handling multiple-priority-class traffic are presented. The new protocols allow the transmission of a varying-length stream of packets with just a single reservation. Two protocols are proposed, one for a system in which the number of active users (contenders) in the currently highest priority class can be determined during the reservation period, and the other for a system in which this number cannot be determined. If the number of active users is known, then optimal p-persistence is used to transmit the packets; otherwise, a dynamically determined combination of one-persistant and p-persistent periods is used to transmit the packets in the reserved priority group and to prevent lower priority users from interrupting the reserved priority transmission stream. Preemptive and nonpreemptive versions of the protocols are described. A simple analytical model is developed and used to obtain channel efficiency as a function of priority group size. Using this model, it is shown that the new protocols allow higher channel utilization than previous, reservation-per-attempted-transmission protocols.>

A file system tailored to the general needs of the office environment is proposed. This system supports large numbers of a wide variety of documents and inexact fuzzy queries on the documents. The file system is based on a multilevel file structure that combines and extends multikey extendible hashing and signature files to create a document-retrieval system that is more time efficient than other previously proposed systems and is also space efficient.>

A file system tailored to the general needs of the office environment is proposed. This system supports large numbers of a wide variety of documents and inexact ‘fuzzy’ queries on the documents. The file system is based on a multilevel file structure; the structure combines and extends multikey extendible hashing and signature files to create a document retrieval system that is more time efficient than other previously proposed systems, and also space efficient.

A new, fully-distributed protocol for integrated voice/data traffic in a local-area, random-access broadcast network is described. The protocol introduces a movable voice-data boundary to framed TDMA/CSMA and eliminates the requirement of system-wide synchronized clocks. The movable boundary is a major advantage in any system where fluctuations in voice and data loads are expected because assignment of idle capacity from one traffic class to the other increases the utilization of the channel. The protocol provides collision-free virtual circuits for voice and periods of non-persistent CSMA/CD for data traffic and call establishment, and can support multi-party calls as well as two-way conversations. The protocol allows variable-size voice packets that have very low overhead and variable-size data packets that may be much longer than voice packets. This is of significant practical advantage over previous work, which has required fixed-size voice and/or data packets, or voice packets with high overhead. A method of dynamically controlling the movable boundary to balance the voice and data traffic is also proposed.