Transmission performance of reservation ALOHA access schemes with variable length packets

We propose a hybrid reservation ALOHA access scheme as an efficient transmission access scheme for variable length packets. A packet group having an integral packet length distribution from 1 to m, where m = 2k for a positive integer k, is divided into a group of m/2‐long fixed length packets and a group of 1 to m/2‐long packets. The fixed length packets become the reservation packets. The remaining packets are transmitted by the ALOHA access scheme. The maximum throughput in this scheme reaches about 0.39. Furthermore, the 2‐multiplexed hybrid ALOHA reservation scheme divides the packet group of packets having packet lengths from 1 to m/2 into m/4‐long fixed length packets and a packet group having packets of lengths of m/4 or less, and transmits the m/4‐long fixed length packets in the second reservation slot and the packets having the remaining lengths in the ALOHA slot to reach a maximum throughput of 0.57. These throughput values are used to study the suitability from the two perspectives of a theoretical analysis and a simulation. Finally, we try to improve the delay performance by assigning a number to the ALOHA slot and efficiently retransmitting the collision packets according to the number table. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 42–51, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10019