Satellite MAC Scheduler for Half-Duplex Uplink Resource Allocation
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Solution Overview
Problem
Satellite communication systems face challenges in managing data flow between multiple user terminals due to propagation delays and half-duplex operation of user terminals, which affect efficient communication with satellites.
Innovation Solution
A medium access control (MAC) scheduler is introduced for satellite-to-user-terminal communications, comprising an uplink scheduler and a downlink scheduler, which generates uplink and downlink maps to allocate radio resources efficiently, considering propagation delays, half-duplex operation, and other constraints like bandwidth and power saving schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If satellite communication is used to enable direct communication between satellite and multiple user terminals, then communication coverage and accessibility are improved, but propagation delays and half-duplex operation constraints arise that reduce communication efficiency
Solution Approach 1:
The MAC scheduler performs preliminary actions by pre-planning and pre-allocating radio resources in time slots before actual data transmission occurs. The scheduler determines which user terminals can transmit or receive data in upcoming time slots, accounting for propagation delays and half-duplex constraints, thereby optimizing communication efficiency while maintaining wide coverage
2Productivity
If multiple user terminals communicate simultaneously with the satellite, then system capacity and data throughput are improved, but timing synchronization and resource allocation complexity increase due to propagation delays
Solution Approach 1:
The MAC scheduler segments the communication process into discrete time slots, allocating specific time periods for different user terminals to transmit or receive data. This segmentation approach manages multiple simultaneous communications by dividing them into organized, non-overlapping time segments, reducing scheduling complexity while maintaining high data throughput
Solution Approach 2:
The MAC scheduler implements dynamic resource allocation that adapts to changing communication conditions. The scheduler continuously adjusts time slot assignments and radio resource allocations based on current system state, user terminal positions, and propagation delay variations, enabling efficient management of multiple simultaneous communications without excessive complexity
3Productivity
If radio resources are allocated to multiple user terminals, then system utilization is improved, but power consumption and resource management complexity increase
Solution Approach 1:
The MAC scheduler implements periodic time-slot-based resource allocation, where radio resources are assigned to multiple user terminals in alternating time periods rather than continuously. This periodic approach enables the satellite to manage power consumption by activating transmissions only when needed in specific time slots, maintaining high system utilization while reducing overall power consumption compared to continuous allocation
Data Source
AI summary
A method for operating a user terminal in a satellite communication system includes receiving an uplink map from a satellite, the uplink map identifying a respective grant of radio resources in an uplink frame for the user terminal and at least one additional user terminal representing a set of user terminals. The uplink map is generated by the satellite. The satellite performs operations comprising: forming the set of user terminals into a plurality of bursts; computing available radio resources for each respective burst of the plurality of bursts; and allocating a respective grant of radio resources to the user terminal based on computing the available radio resources for each respective burst of the plurality of bursts. The user terminal transmits data in the uplink frame allocated for the user terminal based on the uplink map.