Asymmetric Forward Link Subframe Allocation in Satellite Networks
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Solution Overview
Problem
Conventional satellite communication systems face inefficiencies in forward-link throughput due to symmetric allocation of forward-link (FL) and reverse-link (RL) subframes, which does not account for the typically higher volume of FL traffic, leading to suboptimal resource allocation and reduced data transmission efficiency.
Innovation Solution
The proposed solution involves dynamically provisioning communication frames with an asymmetric allocation of FL and RL subframes, allowing for more FL subframes and fewer RL subframes, and configuring at least one RL subframe to provide hybrid automatic repeat request (HARQ) feedback for multiple FL subframes, optimizing resource allocation based on traffic proportions and propagation delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If symmetric allocation of FL and RL subframes is used, then implementation complexity is reduced and HARQ operations are simplified, but forward-link throughput is limited due to equal resource allocation despite higher FL traffic volume
Solution Approach 1:
The patent applies asymmetry by allocating a different number of subframes to forward-link and reverse-link directions within the same communication frame. Specifically, more subframes are assigned to FL transmissions than to RL transmissions, matching the asymmetric traffic pattern where FL traffic volume exceeds RL traffic volume. This resolves the contradiction by optimizing throughput for the dominant traffic direction while maintaining manageable complexity through structured asymmetric allocation.
Solution Approach 2:
The patent implements dynamic frame provisioning where the number of FL and RL subframes can be adjusted based on traffic conditions. The system can dynamically change the allocation ratio between FL and RL subframes to adapt to varying traffic demands, allowing the frame structure to be flexible rather than fixed. This enables the system to optimize for forward-link throughput when FL traffic is dominant while maintaining the ability to adjust when traffic patterns change.
2Productivity
If more FL subframes are allocated to increase throughput, then forward-link data transmission efficiency improves, but the number of available RL subframes for HARQ feedback decreases
Solution Approach 1:
The patent merges multiple FL subframes' HARQ feedback requirements into fewer RL subframes. Instead of dedicating one-to-one RL subframes for each FL subframe's feedback, the system combines feedback for multiple FL transmissions into single RL subframes. This merging approach allows more FL subframes to be allocated for data transmission while maintaining sufficient HARQ feedback capability through consolidated feedback mechanisms.
Solution Approach 2:
The RL subframes are designed to serve multiple functions: they provide HARQ feedback for multiple FL subframes simultaneously, and can also carry other control information. This multi-functionality allows the limited RL subframes to handle feedback for an expanded number of FL subframes, resolving the contradiction between increasing FL throughput and maintaining HARQ feedback availability.
3Productivity
If asymmetric subframe allocation is implemented, then resource allocation optimizes for traffic proportions, but timing synchronization and frequency coordination between FL and RL become more challenging
Solution Approach 1:
The patent segments the communication frame into distinct FL and RL portions with clear boundaries and allocation rules. By dividing the frame structure into identifiable segments with specific subframe allocations, the system manages timing and frequency coordination through structured segmentation rather than complex continuous adjustment. Each segment's parameters can be independently optimized while maintaining overall frame synchronization.
Data Source
AI summary
A method and apparatus for operating a satellite access network (SAN) of a satellite communication system to schedule communications with a user terminal. In some aspects, the SAN may provision a communication frame, for the user terminal, into a number of forward-link (FL) subframes and a different number of reverse-link (RL) subframes. The SAN then transmits the FL subframes to the user terminal via a forward link of the satellite communication system, and subsequently receives the RL subframes from the user terminal via a reverse link of the satellite communication system.