Contact Plan Design For Optical Interplanetary Communications

2026-01-26

AI Summary

This work addresses the critical oversight in existing deep-space optical communication contact plans, which neglect optical terminal repointing delays, leading to overestimated transmission durations and infeasible schedules. To resolve this, we propose the first contact planning framework for optical interplanetary backhaul networks that explicitly integrates the pointing, acquisition, and tracking (PAT) process. Our model captures time-varying directional traffic over both direct and two-hop relay paths and introduces an optical network duty cycle metric to quantify capacity loss due to repointing. Leveraging a mixed-integer linear programming (MILP) scheduler within a delay/disruption-tolerant networking (DTN) architecture, we demonstrate that optimal scheduling favors fewer, longer-duration links to maximize throughput and minimize repointing overhead. Experimental results show over 30% improvement in network capacity compared to greedy approaches, underscoring the necessity of explicitly modeling repointing delays for generating efficient and feasible contact plans.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Algorithms and analysis for incomplete, noisy, or partially observed Web-related graphs
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

Space exploration missions generate rapidly increasing volumes of scientific telemetry that far exceed the capacity of today's manually scheduled, RF-based deep-space infrastructure. Free-space optical (FSO) communications promise orders of magnitude higher throughput, but their narrow beams require precise pointing, acquisition, and tracking (PAT) for link establishment and tightly synchronized contact schedules. Critically, no existing contact plan design (CPD) framework accounts for optical head retargeting delay, the time spent during coarse pointing and link acquisition before data transmission begins, which directly reduces usable contact time. Retargeting delay is the dominant impairment unique to optical networks, which induces a seconds-to-minutes-long mechanical pointing process for an optical terminal's laser from its current partner to the next receiver. This paper introduces the first PAT-aware CPD framework for optical interplanetary backhaul networks. The model captures directional temporal flows across both direct-to-Earth optical links and two-hop relay paths using delay/disruption-tolerant networking (DTN) satellites. We also introduce an optical network duty-cycle metric that quantifies the proportion of time spent transmitting to the contact window duration, exposing capacity lost to retargeting delay. Our results show that our MILP scheduler delivers over 30 percent higher network capacity than a greedy algorithm. More importantly, the results uncover a fundamental behavioral shift: when retargeting delays are modeled accurately, optimal schedules favor fewer but longer optical links that maximize throughput while minimizing retargeting overhead. These findings demonstrate that zero-delay assumptions substantially overestimate achievable performance and yield unrealistic contact plans.

Problem

• contact plan design
• optical interplanetary communications
• retargeting delay
• pointing acquisition and tracking
• deep-space networking

Innovation

• retargeting delay
• optical interplanetary communication
• contact plan design
• PAT-aware scheduling
• duty-cycle metric