An improvement towards the data throughput of CubeSat satellite

Abstract

The unceasing growth in educational CubeSat (a class of nanosatellite) missions emphasize their valuable role, especially in the research sector. They have been shown to effectively contribute to testing and demonstrating new space technologies in a low-cost manner compared to regular satellite missions. As the CubeSat missions are typically used for scientific purposes, there is an essential need for a very high data throughput, especially by considering the few available short communication windows in the CubeSat mission life. Achieving high data throughput is not trivial due to various limitations that restricting the CubeSat potentials. One of the main CubeSat constraints is its limited size, which is mainly (10 x 10 x 11 cm) for one unite CubeSat. This specification reduces the potential of using a powerful antenna system and large size solar panels, which highly contribute to enhancing the data throughput. As a consequence, various researches were conducted on different improvements to advance the CubeSat data throughput such as a new antenna or transceiver design. However, these types of improvements require building new products while in most educational CubeSat missions, the CubeSat components are purchased from off-the-shelf products. In the other hand, many researchers focused on improving the CubeSat communication subsystem using the available off-the-shelf products. These type of researches focused on improving the CubeSat communication protocols. One of the best protocols which have led to high data throughput are the Variable Coding and modulation (VCM), and Adaptive coding and modulation (ACM) techniques. On average, these techniques showed an improvement of almost double the data throughput of a fixed modulation and coding technique. To move beyond that, we have sought to enhance the performance of the VCM/ACM techniques by considering the CubeSat's power features. Altering the power level is a key contributor in the process of selecting the suitable modulation and coding option of the VCM/ACM techniques. Increasing the transmission power is reflected positively in the received signal strength and thus allows for better coding and modulation option. Therefore, in our research, we introduced our approach which is based on the combination of (ACM) and an ii Adaptive Power Control (APC) techniques. APC is designed to suit the CubeSat's power limitations. Assessing the performance of our approach was based on comparing the performance of three main modulation techniques with respect to total data throughput per a communication window, the total number of photos that can be downloaded per a communication window, and the total data throughput per a CubeSat mission. For that, we used a case study methodology for a CubeSat mission. The result showed that by considering the CubeSat's power feature while applying the ACM technique, the total data throughput increased by 35% compared to the Adaptive coding and modulation technique. However, for the total number of photos per a CubeSat mission, the power control achieved a significant increase rate of 80% compared to ACM which is nearly the double. iii

Date of Award	Dec 2017
Original language	American English