Spectrum Rights in Outer Space: Interference Management for Mega-constellations

Abstract

The rapid increase in low earth orbiting, non-Geostationary (NGSO) communication satellites raises concerns related to the coordination of radio frequency access across competing NGSO systems. Responding to an April 2020 petition by SpaceX, the FCC issued a Notice of Proposed Rulemaking NPRM (FCC 21-123) aimed at updating its NGSO spectrum sharing rules in the relevant frequencies (which involve ten distinct bands between 10 and 51 GHz).2 In this paper, we examine the rights regime proposed by the FCC and, guided by empirical evidence, propose alternatives that may better resolve the challenges confronted. Spectrum policy for satellite systems has been a topic for regulators for several decades, and the new satellite system, radio technologies, and spectrum sharing approaches make the topic ripe for reconsideration.

Currently, NGSO Fixed Satellite Service (FSS) spectrum is allocated in processing rounds to qualified applicants without explicit protection for incumbents having rights issued in prior rounds. FCC rules first encourage co-frequency operators in certain bands to resolve interference privately (self-governance); failing coordination agreement, the Commission imposes a “1/n rule”. Under the 1/n approach, if the level of interference (“system noise temperature”) rises above a specified level due to the entry of additional wireless users, then access rights to the band(s) in question will be segmented, each of the n systems given accessto 1/n of the allocated band. This creates a number of implications, including: (1) a potential disincentive to invest in these services given the insecurity of existing access rights; and (2) opportunities to force fragmentation, hobbling competitors’ bandwidth access. This rule also assumes that rival systems value spectrum usage equally, which is unlikely. As a result, alternative approaches may be more economically efficient than the 1/n rule.

Recent innovations in coordinating spectrum sharing, such as database-mediated access or sensing-based approaches, could be relevant here and merit examination in the NGSO context.
Because the FCC’s NPRM proposes to protect systems from prior rounds from those in subsequent rounds, it creates a tiered rights structure similar in some ways to CBRS; services now deployed under this regime may illustrate regulatory options for NGSOs. Finally, we examine the utility of congestion metrics such as interference to noise ratio (I/N), and “system noise temperature” as a basis for the 1/n rule.

Keywords: Satellite, NGSO, FCC, Megaconstellation, Policy

JEL Classification: K2