SIMULATION OF MULTIPLE ACCESS PROTOCOLS FOR MOBILE SATELLITE COMMUNICATION

Abstract

This dissertation presents the performance comparison of versions multiple access protocols suitable for mobile satellite communication applications. Multiple access protocols can broadly be classified into two major categories : random access and reservation access protocols. They have their own merits and demerits according to the type of users and traffic. Two important performance measures used in selecting a suitable multiple access protocol are maximum attainable throughput and mean packet delay. In this dissertation a simulation approach has been used for performance comparison of various protocols. Three protocols namely Packet Demand Assignment Multiple Access (PDAMA), Modified Packet Demand Assignment Multiple Access (MPDAMA) and modified slotted ALOHA have been simulated. PDAMA and modified slotted ALOHA protocols are pure reservation and pure random access schemes respectively, while MPDAMA, a modified version of PDAMA, is a combination of these two. For small packet arrival rates, the performance of the MPDAMA protocol is similar to that of modified slotted ALOHA and better than that of PDAMA protocol. As the packet arrival rate increases, the performance of the MPDAMA protocol improves greatly compared with that of PDAMA protocol. Finally, a further modification in MPDAMA protocol where unused reservation slots in data frame are used in the contention mode has been proposed. Simulation results for this protocol show improvement in performance over MPDAMA.