Satellite Spot Beam Capacity Maximization via Adaptive Modulation
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Solution Overview
Problem
Existing satellite communication systems fail to maximize data-carrying capacity due to inadequate selection of system parameters, particularly in interference-dominated environments, leading to reduced bandwidth efficiency and increased costs from over-designing receivers and using excessive power supplies.
Innovation Solution
The system optimizes data-carrying capacity by employing a specific number of frequency and polarization colors, beam spacing, and adaptive coding and modulation (ACM) to maximize minimum or average capacity within spot beams, even in interference-dominated conditions, using a single-color or two-color beam pattern with regular frequency reuse and non-uniform beam dispersion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the satellite system uses multiple color patterns with frequency division to reduce interference, then the signal quality is improved, but the available frequency bandwidth for each spot beam is reduced and the number of TWTAs required increases
Solution Approach 1:
The patent changes the fundamental parameter of frequency reuse by allowing adjacent spot beams to use the same frequency color instead of requiring different colors. This parameter change enables frequency reuse across adjacent beams, dramatically increasing the available bandwidth per beam while maintaining signal quality through interference management techniques.
Solution Approach 2:
The patent introduces adaptive coding and modulation (ACM) that dynamically adjusts the modulation scheme based on the signal-to-interference ratio at the receiver. This dynamic adaptation allows the system to optimize performance in real-time, managing interference effects and maximizing data-carrying capacity regardless of the frequency allocation scheme.
2Productivity
If the satellite system uses more beams to increase system flexibility and bandwidth efficiency, then the coverage area is expanded, but the number of transponders and amplifiers required increases
Solution Approach 1:
The patent merges the frequency allocation across multiple spot beams by allowing adjacent beams to share the same frequency color. This merging approach enables a smaller number of transponders to serve multiple beams simultaneously, reducing the overall hardware complexity while maintaining high bandwidth efficiency through frequency reuse.
3Reliability
If the receiver is over-designed to cope with worst-case interference conditions, then the reliability is improved, but the cost of subscriber terminals increases
Solution Approach 1:
The patent employs adaptive coding and modulation that dynamically adjusts to the actual interference conditions experienced by each receiver. Instead of designing receivers for worst-case scenarios, the system adapts the modulation scheme based on real-time signal-to-interference ratio measurements, allowing simpler, less expensive receivers to achieve reliable performance.
Solution Approach 2:
The patent changes the operating parameters of the communication system by using frequency reuse with ACM, which transforms the interference environment from a static worst-case scenario to a dynamic manageable condition. This parameter change allows receivers to operate with lower design margins while maintaining reliability.
4Productivity
If the system uses orthogonal polarization to increase bandwidth, then the data-carrying capacity is improved, but the complexity of the frequency re-use pattern increases
Solution Approach 1:
The patent merges polarization multiplexing with frequency reuse by allowing adjacent spot beams to use the same frequency and polarization combination. This merging approach doubles the data-carrying capacity through polarization diversity while avoiding the complexity of sophisticated frequency reuse patterns, as the same pattern can be applied across both polarizations.
Data Source
AI summary
Methods, systems, and apparatuses are presented for improved satellite communications. The satellite system may comprises at least one gateway, a satellite in orbit configured to communicate with the at least one gateway and provide a plurality of spot beams, and a plurality of subscriber terminals. The spot beams may include a first spot beam to illuminate a first region and a second spot beam to illuminate a second region adjacent to and overlapping with the first region. The first spot beam as sent to at least one subscriber terminal may be affected by (1) interference from other signal sources including the second spot beam at a signal-to-interference ratio C/I and (2) noise at a signal-to-noise ratio C/N. Reception of signals from the first spot beam by the at least one of the first plurality of subscriber terminals may be interference-dominated such that C/I is less than C/N.