Virtual Time CSMA Protocols for Hard Real-Time Communication

We study virtual time CSMA protocols for hard real time communication systems, i, e., systems where messages have explicit deadlines. In this class of CSMA protocols, each node maintains two clocks; a real time clock and a virtual time clock. Whenever a node finds the channel to be idle, it resets its virtual clock. The virtual clock then runs at a higher rate than the real clock. A node transmits a waiting message when the time on the virtual clock is equal to some parameter of the message. Using different message parameters in conjunction with the virtual clock, different transmission policies can be implemented. In particular, use of message arrival time, message length, message laxity, and message deadline implements FCFS, Minimum-Length-First, Minimum-Laxity-First, and Minimum-Deadline-First transmission policies, respectively.

[1]  Krithi Ramamritham.  Channel Characteristics in Local-Area Hard Real-Tlime Systems , 1987, Comput. Networks.

[2]  Michel Olivier Scholl,et al.  Multiplexing techniques for data transmission over packet switched radio systems. , 1976 .

[3]  M. Schwartz,et al.  An Assigned-Slot Listen-Before-Transmission Protocol for a Multiaccess Data Channel , 1979, IEEE Trans. Commun..

[4]  Leonard Kleinrock,et al.  Virtual Time CSMA: Why Two Clocks Are Better than One , 1985, IEEE Trans. Commun..

[5]  Hideyuki Tokuda,et al.  A Time-Driven Scheduling Model for Real-Time Operating Systems , 1985, RTSS.

[6]  Leonard Kleinrock,et al.  Packet Switching in Radio Channels: New Conflict-Free Multiple Access Schemes , 1980, IEEE Trans. Commun..

[7]  Ernst A. Rothauser,et al.  MLMA-A Collision-Free Multi-Access Method , 1977, IFIP Congress.

[8]  John Capetanakis,et al.  Tree algorithms for packet broadcast channels , 1979, IEEE Trans. Inf. Theory.

[9]  James F. Kurose,et al.  Time-Constrained Communication in Multiple Access Networks , 1984 .

[10]  John A. Stankovic,et al.  A Perspective on Distributed Computer Systems , 1984, IEEE Transactions on Computers.

[11]  David R. Jefferson,et al.  Virtual time , 1985, ICPP.

[12]  Donald F. Towsley,et al.  Window Random Access Protocols for Local Computer Networks , 1982, IEEE Transactions on Computers.

[13]  Aloysius Ka-Lau Mok,et al.  Fundamental design problems of distributed systems for the hard-real-time environment , 1983 .

[14]  I. Chlamtac,et al.  BRAM: The Broadcast Recognizing Access Method , 1979, IEEE Trans. Commun..

[15]  Yechiam Yemini.  On channel sharing in discrete-time, multi-access broadcast communication , 1979 .

[16]  Wei Zhao.  A heuristic approach to scheduling hard real-time tasks with resource requirements in distributed systems , 1986 .

[17]  Aloysius K. Mok,et al.  Distributed Broadcast Channel Access , 1979, Comput. Networks.

[18]  Leslie Lamport,et al.  Time, clocks, and the ordering of events in a distributed system , 1978, CACM.

[19]  L. Kleinrock,et al.  Packet Switching in Radio Channels: Part I - Carrier Sense Multiple-Access Modes and Their Throughput-Delay Characteristics , 1975, IEEE Transactions on Communications.

[20]  Norman M. Abramson,et al.  THE ALOHA SYSTEM: another alternative for computer communications , 1899, AFIPS '70 (Fall).

[21]  Yechiam Yemini,et al.  Controlling window protocols for time-constrained communication in a multiple access environment , 1983, SIGCOMM.

[22]  J. Hayes,et al.  An Adaptive Technique for Local Distribution , 1978, IEEE Trans. Commun..

[23]  Mart Lauri Molle.  UNificatins and Extensions of the Multiple Access Communications Problem , 1981 .

[24]  GUY FAYOLLE,et al.  Analysis of a stack algorithm for random multiple-access communication , 1985, IEEE Trans. Inf. Theory.