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Broadband LEO Satellite Constellations for Next-Generation Navigation: Potentials, Enabling Technologies, and Challenges

Zhendong Li, Mingze Zhu, Jiahao Liu, Zhou Su, Dong Fu, Ruikang Zhong, Wen Chen

arXiv:2610.02640v1eess.SP

TL;DR

GNSS signals can be weak and vulnerable to blockage, interference, multipath, and spoofing, while broadband LEO systems bring different navigation challenges. This article reviews LEO navigation routes, use cases, technologies, and open challenges; its Starlink PSS case study reports improved ranging robustness while preserving ranging capability.

  • Problem

    GNSS signals can be vulnerable to blockage, interference, multipath, and spoofing, motivating complementary satellite-based PNT.

    Source: §I · p. 1

  • Method

    The article surveys broadband LEO navigation fundamentals, use cases, enabling technologies, and challenges, and presents a Starlink PSS optimization case study.

    Source: §I · p. 2, §VII · p. 7

  • Results

    Optimizing Starlink PSS subcarrier power allocation reshapes spectral energy to improve ranging robustness while retaining ranging capability without fundamentally changing the signal structure.

    Source: §V · p. 6, §VII · p. 7

  • Takeaways & Limitations

    Waveform optimization can improve broadband LEO signal navigation usability, while further advances in receiver processing, resource coordination, and trustworthy PNT are future research directions.

    Source: §VII · p. 7

    Open challenges remain in robust receiver processing, communication-navigation resource coordination, and trustworthy PNT services.

    Source: §VII · p. 7

Abstract

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The rapid deployment of broadband low Earth orbit (LEO) constellations provides new opportunities for next-generation navigation. Compared with conventional global navigation satellite systems (GNSS), broadband LEO systems provide stronger received signals, wider bandwidths, rapidly varying satellite geometry, and larger constellation scales, offering new capabilities for positioning, navigation, and timing (PNT). Meanwhile, their communication-oriented waveforms, high dynamics, and resource-constrained architectures introduce new challenges that are fundamentally different from those in GNSS. This article provides a comprehensive overview of broadband LEO constellations for next-generation navigation, covering their fundamental characteristics, representative use cases, key enabling technologies, and open challenges. We first compare broadband LEO systems with conventional GNSS and summarize the main technical routes for LEO-based PNT. We then discussed the emerging use cases in GNSS-challenged, multipath-dominant, and integrated communication and navigation (ICAN) scenarios. Key enabling technologies including waveform design, high-dynamic signal processing, and constellation resource scheduling are further reviewed. As a representative case study, the navigation-oriented optimization of the Starlink primary synchronization sequence demonstrates that subcarrier power allocation can improve multipath resistance while maintaining ranging accuracy. Finally, several challenges and future directions of broadband LEO-based navigation are discussed, aiming to provide reference for future researches.

I. INTRODUCTION

Broadband LEO constellations offer navigation opportunities through stronger signals, wider bandwidth, and changing satellite geometry. The article reviews their navigation routes, applications, enabling technologies, and challenges.

I. INTRODUCTION

  • LEO’s shorter propagation distance can provide stronger received signals, while wide bandwidth and large constellations offer additional navigation advantages.Prior work reports benefits for signal acquisition and tracking, ranging, and satellite geometry.Source: §I · p. 1
  • Starlink signal acquisition and Doppler-tracking methods demonstrated the feasibility of positioning with multiple Starlink satellites.The stronger received signals associated with LEO can benefit environments affected by blockage, attenuation, and interference.Source: §I · p. 1
  • Broadband LEO waveform bandwidth can improve ranging, although greater bandwidth may increase receiver processing complexity.A broadband massive-MIMO LEO system also jointly considered communications and localization, balancing communication performance and localization accuracy.Source: §I · p. 1
  • Large LEO populations can improve DOP, and experiments combining Starlink, OneWeb, Orbcomm, and Iridium demonstrated stationary and mobile navigation.These developments motivate systematic study of broadband LEO navigation’s fundamental and practical aspects.Source: §I · p. 1
  • The article surveys LEO navigation fundamentals, use cases, enabling technologies, a Starlink signal-optimization case study, and open challenges.Its enabling-technology coverage includes signal and waveform design, signal processing, and constellation design and resource scheduling.Source: §I · p. 2

II. FUNDAMENTALS OF BROADBAND LEO NAVIGATION

Broadband LEO navigation differs from GNSS in system purpose, orbit, signal design, and constellation operation; the section compares these features and introduces navigation routes.

A. Fundamental Differences

  • GNSS is designed for PNT, whereas LEO constellations such as Starlink and OneWeb primarily provide broadband access and optimize resources for communications.Iridium and Orbcomm support narrower-band voice, data, and messaging services.Source: A. Fundamental Differences · p. 2
  • LEO’s shorter propagation distance can reduce path loss, but its smaller coverage footprints require more satellites for stable global coverage.Large communication megaconstellations provide a deployment scale compatible with that requirement.Source: A. Fundamental Differences · p. 2
  • Broadband LEO systems use wideband communication signals and may dynamically allocate resources, while providing less standardized signal, timing, and satellite-state information than GNSS.Narrowband Iridium and Orbcomm signals can also provide useful opportunistic-navigation measurements.Source: A. Fundamental Differences · p. 2

B. Main Advantages

Broadband LEO navigation draws potential benefits from wide bandwidth, rapid satellite motion, and large constellations, though the actual gains depend on signal and geometry conditions.

B. Main Advantages

  • Wide bandwidth provides finer delay discrimination that can improve ranging and help distinguish multipath components with different delays.Actual ranging gain also depends on waveform, spectral shape, signal-to-noise ratio, and receiver processing.Source: B. Main Advantages · p. 2
  • Rapid LEO motion changes satellite-user geometry over short intervals and can shorten carrier-phase ambiguity resolution time.Rapidly changing relative motion can also improve user-state observability.Source: B. Main Advantages · p. 2
  • More visible satellites in large LEO constellations can improve spatial geometry and measurement redundancy, but DOP gains depend on geometry and satellite selection.DOP may vary with altitude, orbital configuration, and satellite visibility.Source: B. Main Advantages · p. 3

C. Technical Routes

Broadband LEO PNT research follows three routes: receiver-side use of communications signals, fusion of complementary navigation sources, and communications-network design that incorporates PNT.

C. Technical Routes

  • Opportunistic navigation extracts PNT observables from existing LEO communication downlinks without modifying the satellite system.It uses synchronization, reference, or other known signal structures; performance depends on signal knowledge and satellite orbit and clock information.Source: C. Technical Routes · p. 3
  • Multisource navigation combines LEO measurements with other sources, including GNSS, to provide complementary availability, geometry, and measurement diversity.Studies report useful LEO positioning support when visible GNSS satellites are limited or GNSS signals are weak.Source: C. Technical Routes · p. 3
  • ICAN design incorporates PNT requirements into communication-system signals, resources, beamforming, and operation, creating tradeoffs that require coordinated design.A proposed framework jointly optimized satellite selection and beamforming to balance communication and navigation performance.Source: C. Technical Routes · pp. 3–4

III. REPRESENTATIVE USE CASES OF BROADBAND LEO NAVIGATION

The section surveys broadband LEO use cases, including resilient PNT where GNSS is degraded. Lower satellite altitude and large constellations can add measurements that support navigation availability, continuity, and resilience.

A. Resilient PNT in GNSS-Challenged Environments

  • Urban canyons, indoor settings, and locally interfered areas can degrade GNSS availability and measurement continuity, while weak signals make acquisition and tracking more challenging.Longer integration times and increased computational complexity may be needed to improve sensitivity.Source: A. Resilient PNT in GNSS-Challenged… · p. 4
  • Lower orbital altitudes provide stronger received signals, and large LEO constellations increase satellite visibility and provide richer satellite–user geometry.Source: A. Resilient PNT in GNSS-Challenged… · p. 4
  • Broadband LEO is framed as a complementary PNT layer, adding measurements that can improve service availability, continuity, and resilience rather than replacing GNSS.Source: A. Resilient PNT in GNSS-Challenged… · p. 4

B. Navigation in Multipath-Dominant Environments

Broadband LEO navigation addresses multipath-dominant settings and can support connectivity and PNT through shared infrastructure. Its use in ICAN entails coordination because communication and navigation performance are coupled.

B. Navigation in Multipath-Dominant Environments

  • Wide bandwidth offers finer delay resolution to distinguish paths, while faster-changing satellite–user–reflector geometry can reduce the persistence of multipath over short observation intervals.These opportunities are particularly relevant when combined with suitable signal processing and waveform design.Source: B. Navigation in Multipath-Dominant… · p. 4

C. PNT Services in ICAN-Enabled Environments

  • Jointly optimized satellite selection and beamforming in a LEO-ICAN network demonstrate a tradeoff between transmission rate and GDOP, motivating coordinated resource allocation.Shared satellite infrastructure can support connectivity and PNT for users requiring both services.Source: C. PNT Services in ICAN-Enabled… · p. 5

IV. KEY ENABLING TECHNOLOGIES FOR BROADBAND LEO NAVIGATION

Broadband LEO navigation depends on adapting communication signals, receiver algorithms, and system resources for PNT. Waveform design is one enabling layer, with flexibility to shape signals and coordinate communication and navigation resources.

IV. KEY ENABLING TECHNOLOGIES FOR BROADBAND LEO NAVIGATION

  • Navigation in communication-oriented LEO systems is coupled to waveform design, high-dynamic signal processing, and constellation resource management.Source: §IV · p. 5

A. Signal and Waveform Design

  • Broadband waveform choices in bandwidth, spectral shape, and power distribution affect ranging accuracy, multipath resistance, interference robustness, and spectral compatibility.Starlink Ku-band downlink is identified as a broadband OFDM signal with predictable synchronization sequences that can support pseudorange and Doppler measurements.Source: A. Signal and Waveform Design · p. 5
  • Joint waveform designs can assign navigation PRN codes and communication data to orthogonal delay-Doppler resources, reducing mutual interference while supporting continuous tracking and reliable communication.Source: A. Signal and Waveform Design · p. 5

B. Signal Processing

The section reviews receiver processing and constellation resource scheduling for LEO dynamics and constraints, then presents a Starlink PSS optimization case study. Its power redistribution suppresses multipath sidelobes while retaining ranging performance.

B. Signal Processing

  • Zak-transform-based coherent acquisition exploits periodic signals’ delay-Doppler structure to mitigate coherent integration loss from Doppler mismatch and improve acquisition efficiency.Tracking must adapt to rapidly varying carrier frequency, code phase, and Doppler rate to avoid loss of lock and preserve measurements.Source: B. Signal Processing · p. 5

C. Constellation Design and Resource Scheduling

  • Navigation-oriented scheduling selects satellites and allocates time, frequency, power, and beam resources according to visibility, geometry, signal quality, and service demand.The allocation must adapt to changing visibility and balance communication throughput against PNT performance.Source: C. Constellation Design and Resource… · p. 5

V. CASE STUDY: NAVIGATION-ORIENTED OPTIMIZATION OF STARLINK SIGNALS

  • The original Starlink PSS has an approximately flat in-band spectrum with sharp band-edge transitions, producing sidelobe oscillations and a long tail that can cause larger errors at medium and long multipath delays.Source: §V · p. 5
  • The case study compares the 240 MHz Starlink signal with bandwidth-comparable scaled BPSK(120) and BOC(60,60) references, using a 250 MHz receiver front-end and a −6 dB multipath-to-direct amplitude ratio.The reference settings are not presented as specific operational GNSS signals.Source: §V · pp. 5–6
  • The optimized PSS shifts subcarrier power from band edges toward the occupied-band center, softening spectral transitions and suppressing autocorrelation sidelobes.Sufficient Gabor bandwidth is retained to preserve ranging capability, trading multipath resistance against ranging accuracy.Source: Figure 3 · p. 6, §V · p. 6
  • The optimized Starlink PSS shows weaker multipath-error oscillations, particularly at medium and long relative delays, while retaining strong ranging performance.At a 250 MHz receiver front-end bandwidth, it retains larger Gabor bandwidth than the considered GNSS reference waveforms.Source: Figure 4 · p. 6, §V · p. 6

A. Robust Receiver Processing

Broadband LEO receivers must handle high Doppler dynamics and wideband processing demands while meeting real-time and complexity constraints. ICAN systems also face coupled communication-navigation resource allocation challenges under asynchronous multi-satellite transmission and changing service needs.

A. Robust Receiver Processing

  • Large Doppler shifts and rapid variation in carrier frequency, phase, and code timing complicate acquisition and tracking, while wideband multi-satellite processing burdens receivers.Doppler compensation, auxiliary information, and advanced tracking loops can improve adaptability but may add computational overhead and implementation complexity.Source: A. Robust Receiver Processing · p. 6

B. Communication-Navigation Resource Tradeoffs

  • ICAN systems must allocate limited resources across communication and navigation services while meeting both sets of performance requirements.Asynchronous multi-satellite transmission further complicates coordination and interference management.Source: B. Communication-Navigation Resource… · p. 6
  • Joint subcarrier and power allocation can mitigate interference, but existing methods are configuration-specific and may not adapt to dynamic links or diverse service requirements.Future work can incorporate real-time link conditions and service requirements into resource adjustment.Source: B. Communication-Navigation Resource… · p. 7

C. Trustworthy PNT Services

Broadband LEO navigation must address trustworthiness alongside positioning accuracy, including integrity, authentication, anomaly detection, and cross-source consistency. The article’s Starlink case study shows that subcarrier power allocation can reshape spectral energy to improve the tradeoff between ranging capability and robustness.

C. Trustworthy PNT Services

  • High positioning accuracy alone does not ensure trustworthy PNT when interference, spoofing, weak authentication, and heterogeneous observation errors complicate verification and anomaly detection.The article calls for integrity monitoring, authentication, anomaly detection, and cross-source consistency validation to support trustworthy and continuous PNT under changing observation quality and potential interference.Source: C. Trustworthy PNT Services · p. 7

VII. CONCLUSION

  • Subcarrier power allocation reshapes spectral energy to improve the tradeoff between ranging capability and robustness, without fundamentally changing the signal structure.The Starlink primary synchronization sequence case study demonstrates this waveform-optimization approach.Source: §VII · p. 7
  • The conclusion identifies robust receiver processing, communication-navigation resource coordination, and trustworthy PNT services as open challenges for future research.Further advances in these areas can enhance the robustness, availability, accuracy, and trustworthiness of broadband LEO-enabled PNT.Source: §VII · p. 7
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