Small satellites are enabling multisatellite missions that were not otherwise possible because of their small size and modular nature [1]. Multiple small satellites can be flown instead of a much bigger and costlier conventional satellite for distributed sensing applications such as atmospheric sampling, distributed antennas [2], and synthetic apertures [3,4]. Missions with multiple small satellites can deliver a comparable or greater mission capability than a monolithic satellite, but with significantly enhanced flexibility (adaptability, scalability, evolvability, and maintainability) and robustness (reliability, survivability, and fault tolerance) [1,5]. Small satellites that weigh less than 10 kg can be broadly classified into nanosatellites (mass between 1 and 10 kg), picosatellites (mass between 0.1 and 1 kg), and femtosatellites (mass less than 100 g) [1,6].

Review of Formation Flying and Constellation Missions Using Nanosatellites

Small satellite systems enable a whole new class of missions for navigation, communications, remote sensing, and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass, and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. The proliferation of small satellites will enable a better understanding of the near-Earth environment and provide an efficient and economical means to access the space through the use of multi-satellite solution. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft, which opens the door to new applications. Future space missions are envisioned to become more complex and operate farther from Earth, and will need to support autonomous operations with minimal human intervention. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space-based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this survey, we present the various research being conducted in the small satellite community for implementing inter-satellite communications based on the open system interconnection (OSI) model. This survey also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link, and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.

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Survey of Inter-Satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Given the increasing number of space-related applications, research in the emerging space industry is becoming more and more attractive. One compelling area of current space research is the design of miniaturized satellites, known as CubeSats, which are enticing because of their numerous applications and low design-and-deployment cost. The new paradigm of connected space through CubeSats makes possible a wide range of applications, such as Earth remote sensing, space exploration, and rural connectivity. CubeSats further provide a complementary connectivity solution to the pervasive Internet of Things (IoT) networks, leading to a globally connected cyber-physical system. This paper presents a holistic overview of various aspects of CubeSat missions and provides a thorough review of the topic from both academic and industrial perspectives. We further present recent advances in the area of CubeSat communications, with an emphasis on constellation-and-coverage issues, channel modeling, modulation and coding, and networking. Finally, we identify several future research directions for CubeSat communications, including Internet of space things, low-power long-range networks, and machine learning for CubeSat resource allocation.

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CubeSat Communications: Recent Advances and Future Challenges

Works on pico-satellites have gained momentum recently, especially those that consider pico-satellites as part of a much larger constellation or swarm. This feature allows pico-satellites to provide high temporal resolution of observational data and redundancy. In particular, it reduces the need for satellite-to-ground communications and, hence, helps save energy and allows the execution of distributed processing algorithms on the satellites themselves. Consequently, satellite-to-satellite or cross-link communication is critical. To realize these advantages, the cross-link antenna employed on pico-satellites must meet many criteria, namely, small size, lightweight, low-power consumption, high gain, wide bandwidth, circular polarization, and beam steerability. To date, no works have examined the suitability of existing planar antenna designs for the use on pico-satellites. To this end, this paper contributes to the literature by focusing on microstrip patch and slot antennas that have the ability to achieve high gain, beam steering, and wide bandwidth. This paper reviews 66 planar antenna designs, which includes 38-patch and 28-slot antennas. In addition, we provide an extensive qualitative comparison of these antennas in terms of their mass, size, gain, beam steerability, type of polarization, operating frequency band, and return loss. In addition, we have evaluated three antenna designs that best address the pico-satellite challenges on a common platform. We find that the asymmetric E-shaped patch antenna design is the most suitable for the use on 2U CubeSats. This is because of its small size ( $34\times 13$ mm $^{2})$ and high gain (7.3 dB). In addition, the E-shaped patch antenna yields a wide −10-dB bandwidth of 2300 MHz and a small return loss of −15.2 dB.

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A Survey and Study of Planar Antennas for Pico-Satellites

Constellations of small satellites now become a great alternative for scientific missions to study Earth. As a result, they should be considered appropriate communication mechanisms to retrieve the data collected. This article studies the possibility to implement TCP and UDP over IP through the use of intersatellite links and distributed ground stations, such as Genso project. We evaluate parameters like delay end-to-end and throughput for different configurations of the QB50 constellation proposed by von Karman Institute for Fluids Dynamics (VKI).

Preliminary internetworking simulation of the QB50 cubesat constellation

Very high throughput satellites (VHTS) are the new trend in satellite communications systems in order to satisfy the increasing demand for both higher throughput and ubiquitous connectivity. Implementing an IP interactive network over a VHTS would enable the satellite to compete with terrestrial networks by offering ubiquitous added value services for end-user traffic. Even so, the simulations presented in this paper show that a 30% of throughput can be lost due to co-channel interferences. In existing interactive satellite networks such as REDSAT or AmerHis, the return uplink transmissions are inherently benefited from the MF-TDMA scheduling to mitigate the co-channel interferences present in VHTS. In such networks dynamic resource assignation (DAMA) is executed at each SuperFrame period (<100 ms). Therefore, any feasible optimization on the scheduling shall be performed in real time. In this paper, two parallel problems are faced at the same time: co-channel interference mitigation and real time scheduling. In particular, two novel interference-aware scheduling algorithms for a DVB-RCS2 return uplink are presented. Despite other previous works, the proposed algorithms are designed on the basis to be executed in real time on a fixed SuperFrame period basis. The performance assessment of the proposed algorithms is carried out through system-level simulations based on realistic satellite scenarios and interactive traffic models using DAMA in real time.

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MF-TDMA Scheduling Algorithm for Multi-Spot Beam Satellite Systems Based on Co-Channel Interference Evaluation

In this paper we review the evolution of satellite based multimedia systems. We focus especially on digital TV technology over satellite. This architecture takes advantage of the broadcasting capability of satellite systems to provide a low cost broadcast link towards a huge population of receivers. This ability makes the system especially suitable for the provision of multimedia services targeted to the mass public, although a return channel must be provided in order to support interactive services. Terrestrial networks like the Integrated Services Digital Network (ISDN) may provide this return channel.

Multimedia systems based on satellite technology

This paper studies the usage of DVB-RCS resource request mechanisms for carrying Internet traffic. An approach based on using rate based (RBDC) requests for traffic with quality of service requirements, and volume based (VBDC) requests for best effort traffic is proposed and evaluated for a corporate scenario.

Evaluation of DVB-RCS Resource Assignment Mechanisms for Internet Traffic Transport

The artisanal fishing activity carried out on the coasts where the production of fish can be exploited is affected by a lack of communication between the vessels in order to provide relevant information related to multiple marine sensor parameters. It is mainly due to the rugged geographic area that causes highly disruptive communication links and in which traditional IP-based communications with transport protocols such as TCP or UDP do not work properly. This paper presents and evaluates a new communications architecture to provide services to marine sensor networks using a disruption tolerant networking (DTN) based solution. We propose a new architecture that takes into account the different vessels densities. We assume a finite sensor population model and a saturated traffic condition where every sensor always has frames to transmit. The performance was evaluated in terms of delivery probabilities, delay and a DTN scenario indicator (DSI) proposed. Through simulations, this paper reveals that Low Density scenery yield greater latency, and more density of nodes has better results. We achieved a successful delivery rate of 74% and a latency of 2 h approximately. Finally indicators shows that high density of nodes is strongly recommended for fishery scenery models.

Carlos Miguel Nieto

Papers

Preliminary internetworking simulation of the QB50 cubesat constellation

MF-TDMA Scheduling Algorithm for Multi-Spot Beam Satellite Systems Based on Co-Channel Interference Evaluation

Multimedia systems based on satellite technology

Evaluation of DVB-RCS Resource Assignment Mechanisms for Internet Traffic Transport

Marine Delay and Disruption Tolerant Networks (MaDTN): Application for Artisanal Fisheries