Delayed random access schemes - An improvement method of delay distributions for packet broadcasting systems

Since random access systems usually have packet delay distributions with long exponential (geometrical) tails, serious disadvantages can arise when the suitable criterion is not the average delay but some high percentile (90 percent) value of delay. Delayed random access schemes are proposed here which improve the delay characteristics. With this modified system, a terminal that has just generated a packet does not enter the random access state immediately; instead it enters after a time delay determined in accordance with a certain procedure. The queuing discipline therefore tends to be like FIFO, and the distribution for transmission delay is improved. For three typical delay time determination procedures, the extensive effect of this modification is shown using the O-ALOHA. The three procedures are found to be effective for improving transmission delay distribution. Practical studies are included showing the implementation of a delayed random access scheme.