SUMMARYThere is an ever present demand for increasingly higher data rates in multi-spot beam satellite networks. This can be enabled, by shifting carrier frequencies to higher bands, such as the Q/V-band, where more bandwidth is available. Furthermore, the available bandwidth has to be used as efficiently as possible, which requires efficient capacity enhancing techniques. The present paper identifies and analyzes ground segment capacity enhancing techniques for ultra high throughput multi-spot beam satellite networks operating in Q/V-band in the feeder link and in Ka-band in the user link. The impact of several capacity enhancing techniques on system performance is analyzed using a realistic time step-based system simulator. Their impact on the ground segment costs is also analyzed. The examined capacity enhancing techniques are as follows: (i) reduced carrier spacing with adjacent channel interference cancellation; (ii) full frequency reuse with co-channel interference cancellation and scheduling; (iii) four different smart gateway diversity techniques and; (iv) employing optical feeder links as an alternative to radio frequency feeder links. The paper shows that these techniques are capable of improving system performance at the expense of an increase in cost related to the complexity and maturity of the applied capacity-increasing technique.

The next five to ten years will see more and more free-space optical communication systems being put into practical use as technologies and techniques continue to mature, particularly in the area of mobile and satellite-to-ground communications. To meet the increasing demand of these types of systems, it is necessary to gain a deeper understanding of the various atmospheric effects at play in a free-space optical link in an effort to mitigate their impact on operational systems. In that context, the German Aerospace Center (DLR) has conducted a number of field trials between a Dornier 228 aircraft and its ground station in Oberpfaffenhofen, just south of Munich, Germany. These field trials have involved the concurrent measurement of atmospheric turbulence using three different techniques: pupil plane imaging, focus spot imaging and Shack-Hartmann wave-front sensing. To ensure the accurate synchronization of measurements between the three techniques, a concerted effort was made in the selection of computer hardware and the development of image acquisition software. Furthermore, power measurements in up-and downlink have been taken to be further correlated with the 3 primary instruments. It is envisioned that the resulting analysis of these measurements shall contribute to the implementation of new adaptive optics techniques to facilitate various air and space communication links. This paper shall describe the overall experiment design as well as some of the design decisions that led to the final experiment configuration.

Sun-synchronous orbit (SSO) satellites serve many important functions, primarily in the areas of Earth reconnaissance and weather. The orbital parameters of altitude, inclination and right ascension which allow for the unique utility of Sun-sync orbit limit these satellites to a very specific region of space. The popularity of these satellite missions combined with the use of similar engineering solutions has resulted in the majority of current Sun-sync satellites within this region having very similar inclinations and altitudes while also spaced around the Equator in right ascension, creating the opportunity for conjunctions at the polar crossing points and a serious safety issue that could endanger long-term sustainability of SSO. This paper outlines the development of a new architecture of SSO zoning to create specific slots separating SSO satellites in altitude, right ascension and time at all orbital intersections while minimizing the limitations on utility. A methodical approach for the development of the system is presented along with the work-to-date and a software tool for calculating repeating ground track orbits. The slot system is intended to allow for continued utility of and safe operation within SSO while greatly decreasing the chance of collisions at orbital intersections. This architecture is put forward as one possible element of a new Space Traffic Management (STM) system with the overall goal of maintaining the safe and continued used of space by all actors.

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The value of increasing student input to learning opportunity design issues was explored through an action research project. In response to student identified learning needs, a learning session on a first–year undergraduate research methods module was re–designed. The learning outcomes of two parallel student groups (one experiencing the original session, the other receiving the re–designed session) were compared by quantitative analysis. A significant improvement in assessment grades was found for the group receiving the re–designed session. Brief qualitative analysis of student feedback revealed this group’s increased positive course perceptions. The action research project outcomes are discussed within the context of student versus staff control over learning, highlighting the mutual benefits of reflective practice for newer learning facilitators.