Satellite TDD Scheduling for Half-Duplex UEs in FDD Networks
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Solution Overview
Problem
In satellite communications systems, the large propagation delay introduces significant overhead due to the need for large gap periods in time division duplexing (TDD), leading to inefficient use of network resources when using half duplex user equipment.
Innovation Solution
Implementing a full duplex gateway terminal with a scheduler that allocates DL and UL time slots based on propagation delays to avoid overlaps at half duplex user equipment, allowing efficient resource utilization without requiring each UE to be full duplex.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If frequency division duplexing (FDD) is used to provide simultaneous full-duplex communication, then bidirectional communication capability is improved, but radio frequency (RF) hardware complexity and cost increase due to requiring separate receive and transmit RF chains
Solution Approach 1:
The patent merges the receive and transmit RF chains by using a single RF chain that operates in TDD mode, combining the functions of separate receive and transmit hardware into one shared resource that alternates between receiving and transmitting in different time slots
Solution Approach 2:
The single RF chain is designed to perform multiple functions - it can both receive and transmit signals, serving dual purposes that in FDD would require separate dedicated hardware chains for each direction
2Device complexity
If time division duplexing (TDD) is used to reduce RF hardware complexity, then device complexity is reduced, but full-duplex communication capability is degraded due to sequential rather than simultaneous transmission
Solution Approach 1:
The patent introduces dynamic beamforming and spatial multiplexing capabilities that allow the single TDD RF chain to dynamically serve multiple users simultaneously in different spatial directions, making the system behavior adapt between half-duplex and full-duplex operation modes based on channel conditions and user distribution
Solution Approach 2:
The patent adds the spatial dimension to the traditional time-division approach by using multiple antennas and spatial multiplexing, allowing simultaneous communication with different users in different spatial directions during the same time slot, effectively recovering full-duplex capability without requiring separate RF chains
3Adaptability or versatility
If separate receive and transmit RF chains are used in FDD, then simultaneous full-duplex communication is enabled, but power consumption increases due to maintaining both RF chains continuously active
Solution Approach 1:
The patent combines the receive and transmit RF chains into a single shared RF chain that alternates between receiving and transmitting modes, eliminating the need to maintain two separate continuously active RF chains and thereby reducing overall power consumption
Data Source
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AI summary
Described herein are technologies that utilize full duplex gateway terminals in satellite networks with half duplex user equipment. The disclosed scheduling technologies incorporate the knowledge of the propagation delay between a gateway terminal and each UE in communication with the gateway terminal. Based on this propagation delay, a scheduler can allocate DL and UL time slots in a scheduling frame in a way that avoids allocating overlapping DL and UL time slots at each UE.