Technological trends and future prospects of satellite communications for mega-constellations with small satellites

2014 ◽  
Vol 23 (10) ◽  
pp. 1450148 ◽  
Author(s):  
DANIELE DAVALLE ◽  
RICCARDO CASSETTARI ◽  
SERGIO SAPONARA ◽  
LUCA FANUCCI ◽  
LUCA CUCCHI ◽  
...  

This paper presents a flexible Telemetry, Tracking & Command (TT&C) transponder for Earth Observation (EO) small satellites. The proposed device adds to the state-of-the-art EO TT&C transponders the possibility of scientific data transfer thanks to the high downlink data-rate (up to 40 Mbps) and in-flight reconfigurability via Telecomand (TC). The integration of these features in one single device represents a considerable optimization in terms of mass budget, which is important for EO small satellites. Furthermore, in-flight reconfigurability of communication parameters via TC is important for in-orbit link optimization, which is especially useful for Low-Earth Orbit (LEO) satellites where visibility can be as short as few hundreds of seconds. The proposed transponder is a digital radio unit working at 70 MHz intermediate frequency (IF). A new custom and configurable hardware accelerator was developed to cover intensive radio DSP functions at IF. The custom hardware is integrated in a single FPGA with a space-compliant processor core, for control, configuration and interface with the other satellite subsystems. All the quantization parameters were fine-tailored to reach a trade-off between hardware complexity and implementation loss (IL). The IF RX/TX ports require eight bits and seven bits, respectively. The IL is 0.5 dB at BER = 10-5 for the RX chain. A system proof-of-concept was implemented on the Xilinx Virtex 6 VLX75T-FF484 FPGA. The total device occupation is 82%. The power consumption of the design fitted in FPGA is less than 2 W. The power consumption of the whole demonstrator board is less than 9 W.


Author(s):  
Radhika Radhakrishnan ◽  
Qing-An Zeng ◽  
William E. Edmonson

Small satellite technology has opened a new era in aerospace engineering by decreasing space mission costs, without greatly reducing the performance. The concept of formation flying using small satellites is becoming popular because of their potential to perform coordinated measurements of remote sensing space missions. The current state of art in satellite communications is a one hop link between satellite and ground station. Very little work has been done on inter-satellite communications. This paper aims to design and evaluate feasible MAC and routing layer protocols for distributed small satellite networks. The possibility to implement proposed MAC and routing protocols for two different formation flying patterns are investigated. To validate the authors’ proposed system model, they use extensive simulations to evaluate the performance of the system using throughput, access delay and end-to-end delay.


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