Uplink Timing Control Signal Synchronization
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Solution Overview
Problem
Maintaining timing synchronization between wireless terminals and base stations in OFDM wireless communication systems is challenging, especially when wireless terminals move and propagation delays vary, leading to interference issues.
Innovation Solution
The system employs an access channel timing control segment using a combination of non-contiguous and contiguous tone sets to transmit timing control signals, allowing the base station to determine the arrival time of signals with finer granularity and generate timing correction commands to synchronize wireless terminals with the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing synchronization is maintained using traditional methods in OFDM systems, then signal orthogonality is preserved, but timing errors occur when wireless terminals move and propagation delays vary
Solution Approach 1:
The patent implements a feedback mechanism where the base station measures the arrival time of uplink signals from wireless terminals and sends timing adjustment commands back to the terminals. This closed-loop feedback system continuously corrects timing errors caused by terminal movement and propagation delay variations, maintaining synchronization reliability while adapting to changing conditions.
2Measurement precision
If a single tone set is used for timing measurement, then the system is simple, but timing measurement precision is insufficient
Solution Approach 1:
The patent divides the timing measurement process into two segments: a first tone set (non-contiguous tones) for fine timing measurement and a second tone set (contiguous tones) for coarse timing measurement. This segmentation allows the system to achieve high timing precision by combining the advantages of both tone set configurations without requiring a single complex tone set.
Solution Approach 2:
Different parts of the frequency spectrum are assigned different functions: non-contiguous tones are used where fine resolution is needed for precise timing measurement, while contiguous tones are used where coarse estimation suffices. This local quality differentiation optimizes overall timing measurement performance while managing system complexity.
Data Source
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AI summary
The claimed subject matter relates to systems and methodologies for synchronizing timing between a base station and a wireless terminal. For example, a set of non-contiguous tones may be assigned to the terminal, and may be equally spaced apart from each other across a spectrum of all available tones. A set of contiguous tones may also be assigned to the terminal, which may transmit a timing control signal during a specified transmit time. A base station may receive the signal, which comprises information related to the non-contiguous and contiguous tone sets, and may determine a distance of the terminal to the base station based on measured and anticipated arrival time of the signal. The base station may transmit a timing correction command signal to the terminal based on such information.