R-ALOHA with priority (PR-ALOHA) in non ideal channel with capture effects

The performance of reservation ALOHA (R-ALOHA) with priority is analyzed using computer simulation. Priority is introduced to the R-ALOHA protocol by reserving specific time slots in the frame exclusively for high priority traffic. Traffic is produced and divided into either low or high priority. We considered non ideal channel with communication errors and capture effects. Performance is measured in terms of packet throughput and message transfer delay for each priority level. The analysis gives results for varying numbers of reserved high priority slots and varying levels of high priority traffic ultimately leading to a dynamic high priority slot reservation scheme. Multipriority protocols are important in such applications as intervehicle communication, where high priority may represent safety related messages, and multimedia communication, where high priority is given to streaming audio or video. In both applications low delay and high throughput are absolutely necessary for standard performance. The simulation results indicate that as the number of slots reserved for high priority traffic increases the delay of the high priority messages decreases. However, low priority throughput decreases and its delay increases.