Prioritized access in CSMA networks: a node partitioning approach

The authors address the problem of incorporating message-based priority classes in random access protocols. The organization of these classes is based on the different packet delay requirements of higher-layer applications. A novel node-partitioning mechanism to restrict contention only to higher priority packets is introduced. The authors describe node-partitioning carrier-sense multiple access (NP-CSMA), a protocol that uses CSMA as its base access mechanism, and incorporates three priority mechanisms that influence different aspects of the channel access. These are node partitioning, priority queueing at station buffers, and prioritized persistence. A detailed simulation model is described. Simulation studies that demonstrate the effect of these mechanisms, separately and in concert, on the throughput and delay of the various priority classes are presented. It is shown how desired performance can be achieved by suitable variation of protocol parameters