Virtual Time CSMA Protocols for Hard Real-Time Communication
IEEE Transactions on Software Engineering
A Window Protocol for Transmission of Time-Constrained Messages
IEEE Transactions on Computers
CSIM: a C-based process-oriented simulation language
WSC '86 Proceedings of the 18th conference on Winter simulation
Dynamic real-time channel establishment in multiple access bus networks
Computer Communications
Deterministic protocols for real-time communication in multiple access networks
Computer Communications
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Distributed hard real-time systems are characterized by communication messages associated with timing constraints, typically in the form of deadlines. A message should be received at the destination before its deadline expires. Carrier sense multiple access with collision detection (CSMA/CD) appears to be one of the most common communication network access schemes that can be used in distributed hard real-time systems. In this paper, we propose a new real-time network access protocol which is based on the CSMA/CD scheme. The protocol classifies the messages into two classes as 'critical' and 'noncritical' messages. The messages close to their deadlines are considered to be critical. A critical message is given the right to access the network by preempting a noncritical message in transmission. Extensive simulation experiments have been conducted to evaluate the performance of the protocol. It is shown that the protocol can provide considerable improvement over the virtual time CSMA/CD protocol proposed for hard real-time communication by Zhao et al.^1.