RRU Channel Synchronization for High-Speed Rail LTE Systems
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Solution Overview
Problem
In high-speed rail LTE systems, conventional multi-cell combination technology leads to synchronization failures due to varying signal power and delay, causing the terminal to switch between RRU channels frequently, resulting in mismatched channels for uplink demodulation and TA adjustment, which degrades performance.
Innovation Solution
A synchronization method where the base station selects the RRU channel with the highest receiving power, uses a counter to determine consecutive highest power instances, and only switches the RRU channel state when the count reaches a threshold, ensuring timely TA command transmission to maintain synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base station transmits TA command word periodically with short periodicity, then the synchronization accuracy is improved, but the time and frequency resources are occupied, increasing base station processor load and degrading cell-level throughput
Solution Approach 1:
The patent implements periodic TA command transmission but dynamically adjusts the periodicity based on terminal mobility state. For high-speed terminals, the periodicity is extended while maintaining synchronization through event-triggered updates when channel conditions change significantly, resolving the conflict between frequent updates and resource efficiency
Solution Approach 2:
The base station changes the transmission parameters of TA command words based on terminal speed and channel conditions. By adjusting periodicity and triggering conditions dynamically, the system achieves high synchronization accuracy for moving terminals without permanently occupying excessive resources, thus maintaining cell-level throughput
2Measurement precision
If the terminal switches between RRU channels frequently to track highest signal power, then the signal reception quality is improved, but the synchronization between base station and terminal fails due to channel mismatch for uplink demodulation and TA adjustment
Solution Approach 1:
The patent introduces an RRU channel state indication mechanism as an intermediary. The base station identifies which RRU channel the terminal is using and sends corresponding TA commands through the appropriate channel. This mediator ensures that TA adjustment and uplink demodulation remain synchronized with the terminal's current RRU channel, preventing synchronization failure even during frequent channel switching
Solution Approach 2:
The system implements feedback by having the base station monitor terminal channel switching behavior and adjust TA command transmission accordingly. When the terminal switches RRU channels, the base station detects this through SRS measurements and updates TA commands through the new channel, maintaining continuous synchronization despite frequent switching
3Loss of time
If the base station uses conventional multi-cell combination technology with multiple RRUs covering a cell, then the signaling overhead from frequent handover is reduced, but the signal power and delay vary quickly causing terminal to switch states frequently between RRUs
Solution Approach 1:
The patent makes the RRU channel selection dynamic by having the terminal continuously measure signal power from multiple RRUs and switch to the one with highest power. The base station similarly dynamically identifies which RRU has the strongest terminal signal and routes TA commands through that channel, adapting to changing channel conditions without requiring full handover procedures
Data Source
AI summary
The invention relates to the technical field of communications, and more particularly, to a method and device for realizing synchronization. The method comprises: performing, by a base station, and according to an SRS signal transmitted by a terminal, filtering to obtain a RRU channel having the maximum receiving power in a current operation; upon determining that the RRU channel having the maximum receiving power in the current operation is different from a RRU channel used in the currently performed demodulation, refraining from performing immediate switching; and permitting switching of the RRU channel only when the receiving power of the RRU channel is determined to match the maximum threshold of a preset series of thresholds, and transmitting a TA command word to the terminal while switching the RRU channel to complete synchronization with the terminal. The invention prevents a terminal from frequently switching between RRU channels on a subframe basis. Moreover, a TA command word is transmitted while switching is being performed, thereby preventing a problem in which when a change in a RRU channel occurs, a TA command word is not received by a terminal for a long time, resulting in an asynchronous operation.