Adaptive Radio Channel Estimation for LTE Tune-Away Latency
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Solution Overview
Problem
Existing wireless communication devices face performance degradation due to interruptions in radio channel measurements, as they either accept degradation or restart channel estimation from scratch, failing to adaptively recover from tune-away or sleep modes, leading to inefficiencies in signal reception and power consumption.
Innovation Solution
The method involves determining the duration of reception interruption to select an appropriate channel estimation window length and shape, using a tiered scheme based on thresholds, noise estimates, and radio channel characteristics, such as Doppler shift, to perform adaptive channel estimation, reducing latency and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If channel estimation is restarted from scratch after interruption, then channel estimation accuracy is improved, but channel recovery latency increases
Solution Approach 1:
The patent applies preliminary action by maintaining channel estimation parameters (such as channel impulse response and power delay profile) in memory during interruption periods, so that when reception resumes, the device can resume estimation from the last known state rather than starting from scratch. This reduces channel recovery latency while maintaining accuracy through continued refinement from the saved state.
Solution Approach 2:
The patent implements feedback mechanisms where the device monitors reception quality metrics (such as signal-to-noise ratio and channel quality indicator) and uses this information to dynamically adjust channel estimation parameters. This feedback loop enables the system to recover channel estimation efficiently by leveraging recent quality information while adapting to channel changes during interruption.
2Measurement precision
If channel estimation continues during tune-away or sleep mode, then channel estimation accuracy is maintained, but power consumption increases
Solution Approach 1:
The patent applies periodic action by performing channel estimation only during active reception periods and saving the results for later use during tune-away or sleep modes. The system periodically updates channel estimation parameters when reception is available, then relies on these saved parameters during interruption periods, reducing power consumption while maintaining estimation accuracy through periodic refinement rather than continuous operation.
Solution Approach 2:
The patent uses preliminary action by pre-calculating and saving channel estimation parameters during active periods so that they are available when the device returns from interruption. This eliminates the need for continuous channel estimation during sleep or tune-away modes, significantly reducing power consumption while maintaining accuracy through the pre-computed parameters.
3Device complexity
If a fixed channel estimation window is used, then processing complexity is reduced, but adaptability to channel changes during interruption is worsened
Solution Approach 1:
The patent applies dynamics by making the channel estimation window parameters (such as window length and shape) adjustable rather than fixed. The system dynamically adapts these parameters based on reception quality metrics and interruption duration, allowing the estimation window to expand or contract according to actual channel conditions. This provides adaptability to channel changes while maintaining manageable processing complexity through algorithmic adjustments rather than complete redesign.
Solution Approach 2:
The patent implements parameter changes by modifying channel estimation parameters (such as window length, window shape, and weighting factors) based on reception quality and interruption characteristics. The system changes these parameters adaptively to match current channel conditions, improving versatility while controlling complexity through parameter adjustment rather than fundamental algorithmic changes.
Data Source
AI summary
Methods and apparatus for resuming radio channel measurements and estimations after an interruption in reception. In one exemplary embodiment of the present disclosure, an adaptive solution is provided for channel estimation based at least in part on the reception interruption duration. In one variant, an LTE UE determines a windowing length and/or “shape” for a time domain channel estimation algorithm based on at least the interruption duration. In an alternate variant, an LTE UE determines the interpolation coefficients for a filter based on the interruption duration.