Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View (1609.08583v2)

Abstract: 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.

• The paper presents a comprehensive survey of inter-satellite communication in small satellites, highlighting challenges across the physical, data link, and network layers.
• The authors analyze frequency allocation, modulation techniques, and SDR applications at the physical layer while evaluating MAC protocols for the data link layer.
• They propose dynamic routing strategies and DTN protocols at the network layer to support autonomous operations and scalable satellite constellations.

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

The paper "Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View" offers a detailed examination of the recent advancements and ongoing research efforts in the field of inter-satellite communications specifically tailored for small satellite systems. The investigation addresses challenges at various levels of the OSI model, emphasizing the physical, data link, and network layers, thus providing a comprehensive understanding of the architecture necessary for effective inter-satellite communication.

Key Findings and Research Contributions

The authors categorize small satellites based on their mass, ranging from mini-satellites to femto-satellites, and outline the significance of deploying these satellites in constellations or clusters to enhance spatial and temporal resolution for various science missions. The paper suggests that a multi-satellite approach could lead to cost-efficient and effective mission executions.

Inter-satellite Communication (ISC) is underscored as a pivotal element in future space missions. As autonomous satellite operations become more prevalent, dynamic routing, node management, and self-reconfiguration capabilities are asserted to be requisite capabilities for fulfilling mission objectives. The paper reviews historical data from 2000 to 2015, systematically categorizing research contributions by focusing on the first three layers of the OSI model:

1. Physical Layer: The paper explores frequency allocation and achievable data rates for inter-satellite links, presents challenges in modulation and coding schemes suited for small satellites, and reviews antenna design considerations with respect to size and operational constraints. The potential use of Software Defined Radios (SDRs) is highlighted as a mechanism to address dynamically changing space communication needs due to its flexibility and reconfigurability.
2. Data Link Layer: A thorough analysis of multiple access methods and Medium Access Control (MAC) protocols suitable for small satellite constellations is provided. The authors discuss both contention-based (e.g., CSMA, Aloha) and collision-free techniques (e.g., TDMA, FDMA), concluding that hybrid approaches like TDMA/CDMA offer promising results balancing efficiency and scalability.
3. Network Layer: The authors explore routing strategies critical for ensuring seamless data communication across dynamically changing satellite networks. They propose leveraging Delay-Tolerant Networking (DTN) protocols to address the inherent challenges posed by intermittent connectivity and long propagation delays in space environments.

Implications and Future Directions

The paper indicates significant potential for advancements in autonomous satellite operations, stressing the importance of robust protocols that accommodate dynamic topologies and support high data rate communications. The modularity and scalability of proposed systems, including modular antenna concepts for formation flying, suggest pathways for smoothly integrating new technologies into small satellite constellations.

In conclusion, while the landscape of inter-satellite communication continues to evolve, there is a clear indication of the benefits that flexible communication architectures and cross-layer optimization strategies could provide. The insights from this paper are expected to go a long way in reducing latencies, improving bandwidth efficiency, and ensuring comprehensive coverage for future small satellite missions. The authors advocate for continued exploration in agent-based computing platforms and cross-layer designs that closely align with the unique challenges presented in space communication scenarios.

Continued research in these areas is essential to fully harness the potential of small satellite systems, paving the way for innovative applications and services in both scientific and commercial domains. As small satellite technology advances, it will be imperative to address existing gaps, particularly regarding resource allocation, standardized communication protocols, and security, to realize the vision of robust and reliable inter-satellite communication networks.