Wireless Timing Synchronization via Round Trip Time Compensation
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Solution Overview
Problem
Current synchronization techniques in LTE networks fail to achieve accurate timing synchronization due to the lack of knowledge about propagation delays, especially in indoor deployments and scenarios with multipath propagation, leading to synchronization errors that do not meet the required accuracy for TDD systems and other applications.
Innovation Solution
A method and system that determine the clock offset for a target node by calculating the round trip time of radio signals exchanged between the source and target nodes, compensating for propagation delays and internal processing delays, using reference signals like PSS, SSS, or PRS, and configuring muting patterns to ensure orthogonal transmission and reception times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current synchronization techniques are used in LTE networks, then network operations can proceed with existing infrastructure, but synchronization accuracy is insufficient due to lack of propagation delay knowledge
Solution Approach 1:
The patent implements a feedback mechanism where timing advance commands are sent from the network to the UE based on uplink timing measurements. The UE adjusts its transmission timing based on this feedback, creating a closed-loop system that continuously refines synchronization accuracy by compensating for propagation delays.
Solution Approach 2:
The patent replaces traditional mechanical/GNSS-based synchronization systems with a wireless feedback-based timing adjustment mechanism. Instead of relying on physical clock synchronization or satellite-based timing, the system uses electromagnetic signal exchange and digital timing commands to achieve synchronization.
2Adaptability or versatility
If indoor deployments and multipath propagation scenarios are considered, then network coverage is expanded, but synchronization errors increase due to unknown propagation delays
Solution Approach 1:
The UE performs self-adjustment of its transmission timing by processing timing advance commands received from the network. Each UE independently calculates and applies its own timing correction based on measured round-trip delays, allowing the system to adapt to various deployment scenarios without centralized reconfiguration.
Solution Approach 2:
The system dynamically changes the timing parameter of uplink transmissions based on measured propagation conditions. The timing advance value is adjusted in response to changing channel conditions, mobility states, and deployment environments, allowing adaptation to indoor, outdoor, and multipath scenarios.
3Measurement precision
If timing advance mechanisms are implemented, then uplink synchronization is improved, but additional signaling overhead is introduced
Solution Approach 1:
The timing advance mechanism serves multiple functions: it provides uplink synchronization, enables accurate random access procedure timing, supports handover timing coordination, and facilitates uplink-downlink timing alignment in TDD systems. This multi-functionality justifies the signaling overhead by delivering comprehensive timing control benefits.
Solution Approach 2:
The network periodically sends timing advance commands to UEs to maintain synchronization, especially during mobility events or channel condition changes. This periodic adjustment approach balances the need for synchronization accuracy with the overhead of signaling, adjusting timing only when necessary rather than continuously.
Data Source
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AI summary
A method and nodes for wireless timing synchronization of a target node and a source node. In some embodiments, a request is sent to a source node for time synchronizing the target node with the source node. A first time, T1, indicative of time of transmission of a first radio signal from the source node to the target node is determined. A second time, T2, indicative of time of receipt of the first radio signal at the target node is determined. A third time, T3, indicative of time of transmission of a second radio signal from the target node to the source node is determined. A fourth time, T4, indicative of time of receipt of the second radio signal at the source node is determined. A clock offset based on T1, T2, T3 and T4 for use in time synchronizing the target node with the source node is determined.