Analysis of the LonTalk/EIA-709.1 channel performance under soft real-time requirements

The investigation how to optimize the LonTalk/EIA-709.1 media access protocol in terms of the soft real-time requirements is presented. As a criterion of usage of the LonWorks networks under soft real-time requirements we assume that either the probability of collision, or the jitter of the access delay must be bounded and small enough. The arguments for selection of the unacknowledged service as the most suitable for real-time services are put forward. The simulation results of the collision rate and the mean access delay as a function of the offered load are presented. The delay jitter for light traffic load is evaluated. Two analytical models for the probability of packet collision are suggested. The one is based on the classical approach and used for light traffic conditions. The other is employed for steady-state heavy load. The conclusions present recommendations for designing soft real-time applications using LonTalk/EIA-709.1 channel.