NTRS - NASA Technical Reports Server

Back to Results
Resource sharing on CSMA/CD networks in the presence of noiseResource sharing on carrier sense multiple access with collision detection (CSMA/CD) networks can be accomplished by using window-control algorithms for bus contention. The window-control algorithms are designed to grant permission to transmit to the station with the minimum contention parameter. Proper operation of the window-control algorithm requires that all stations sense the same state of the newtork in each contention slot. Noise causes the state of the network to appear as a collision. False collisions can cause the window-control algorithm to terminate without isolating any stations. A two-phase window-control protocol and approximate recurrence equation with noise as a parameter to improve the performance of the window-control algorithms in the presence of noise are developed. The results are compared through simulation, with the approximate recurrence equation yielding the best overall performance. Noise is even a bigger problem when it is not detected by all stations. In such cases it is possible for the window boundaries of the contending stations to become out of phase. Consequently, it is possible to isolate a station other than the one with the minimum contention parameter. To guarantee proper isolation of the minimum, a broadcast phase must be added after the termination of the algorithm. The protocol required to correct the window-control algorithm when noise is not detected by all stations is discussed.
Document ID
Document Type
Dinschel, Duane Edward (Illinois Univ. Urbana-Champaign, IL, United States)
Date Acquired
August 16, 2013
Publication Date
November 17, 1987
Publication Information
Publication: Presentation Slides and Publications. NASA Review of ICLASS: Illinois Computer Laboratory for Aerospace Systems and Software
Subject Category
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
Document Inquiry