Multi-Satellite Collaborations: Conception, Merits, Mechanisms, and Prospects

As tasks become more diverse and business volume surges in satellite communication scenarios, improving the performance and coordination capabilities of satellite communication systems has become crucial. Satellite communications (SatComs) are characterized by specialized tasks, orbital operation, extensive coverage, and complex link environments. However, relying on a single satellite can introduce performance bottlenecks and coverage blind spots. To address these limitations, this paper explores multi-satellite collaboration (MSC) within space information networks. MSC defined as the coordinated operation of two or more satellites within a given spatiotemporal region, with or without ground node assistance, has therefore emerged as a trans-formative paradigm to jointly accomplish specific missions. First, we analyze the applicability boundaries of single-satellite and MSC modes, highlighting the intrinsic advantages of collaborative architectures for coverage enhancement and resilience. Then, we comprehensively review key enabling technologies for collaboration across various orbital scenarios, including intra-orbit and inter-orbit, as well as network formation and topology construction, signal level, access level, link level, routing level, and transmission resource allocation. We also discuss how emerging technologies, such as artificial intelligence and cross-domain integration, can improve MSC performance. The paper aims to provide theoretical references and technical directions for designing and optimizing future efficient and intelligent MSC systems.