Abstract

There is considerable interest at this time in developing small satellites for quick-turnaround missions to investigate near-earth phenomena from space. The aim of the thesis is to investigate issues related to the migration from current Pre-planned Multiple Access operation mode to the next generation on-demand mode focusing on spacecraft in near earth orbits. In this thesis, an evolutionary on-demand mode network architecture is proposed. One of the most important design issues is the development of medium access control (MAC) schemes. For this new scenario, to meet the objective of the bandwidth-efficient support while guaranteed specific QoS requirements, a detailed investigation of the suitability of the MAC schemes is performed. Performance measures of interest include end-to-end delay, successful throughput and channel efficiency. The general protocol investigation framework is first given. Reservation-based Demand TDMA protocol is proposed for the dynamicLEO scenario. Performance evaluations are performed by means of simulation. We compare the system’s performance under Reservation-based demand-assigned multiple-access channel allocation schemes with that obtained under fixed-assigned scheme. Simulation results demonstrate that on-demand mode is a suitable strategy for next-generation NASA space mission with unpredictable traffic pattern, and can offer certain performance advantages. ON-DEMAND MULTIPLE ACCESS

Citations