Dynamic Time Division Duplex Controller for Satellite Uplink Synchronization
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Solution Overview
Problem
The implementation of Time Division Duplex (TDD) in satellite communications requires precise timing and synchronization to avoid overlapping uplink and downlink signals, which can lead to interference and errors.
Innovation Solution
The Dynamic Time Division Duplex (DTDD) system employs a controller that dynamically adjusts the timing and frequency allocation for uplink and downlink signals, ensuring that signals do not overlap at the satellite or user equipment, even with varying path lengths and orbital positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If TDD uses a single frequency band for both transmit and receive, then spectrum efficiency is improved and no guard bands are needed, but precise timing and synchronization are required to avoid signal overlap and interference
Solution Approach 1:
The patent implements dynamic time division duplex (DTDD) where the base station dynamically adjusts uplink time slots based on unique delays for each user equipment. This dynamic timing adjustment ensures that uplink signals from different UEs arrive at the satellite during the same satellite uplink time slot without overlapping with downlink signals, resolving the contradiction between spectrum efficiency and signal interference
Solution Approach 2:
The system uses feedback mechanisms where the base station receives information about signal arrival times and adjusts uplink time slot assignments accordingly. This feedback loop enables continuous optimization of timing synchronization to prevent signal overlap while maintaining efficient spectrum utilization
2Productivity
If TDD alternates transmission and reception over time with variable time slots, then spectrum usage is optimized, but very precise timing and synchronization systems are needed at both transmitter and receiver
Solution Approach 1:
The patent changes the timing parameter dynamically by adjusting uplink time slot assignments based on unique delays calculated for each user equipment. This parameter adjustment allows the system to maintain precise synchronization without requiring overly complex synchronization systems, as the timing is adapted to match actual signal propagation conditions
3Reliability
If uplink time slots are established based on unique delay for each UE, then signal overlap at satellite is avoided, but dynamic timing adjustment increases base station complexity
Solution Approach 1:
The base station performs preliminary calculations to determine unique delays for each user equipment before establishing uplink time slots. By pre-calculating and pre-assigning timing parameters based on estimated propagation delays, the system avoids signal overlap without requiring continuous complex adjustments during operation
Data Source
AI summary
A ground station communicates with a satellite having a field of view (FOV), the satellite directly communicating with user equipment (UE) over uplink signals and downlink signals. The ground station has a Dynamic Time Division Duplex (DTDD) controller configured to establish UE uplink time slots during which the UE sends UE uplink signals, the UE uplink time slots based on a unique delay for the UE, whereby UE uplink signals are received at the satellite during a same satellite uplink time slot. The controller avoids overlapping uplink and downlink signals being received at the satellite, as well as at the UE.