Decoder Metric Thresholding for False-Alarm Data Presence Detection
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Solution Overview
Problem
In 3rd generation radio access networks, blind transport format detection using cyclic redundancy check (CRC) often results in false alarms, leading to incorrect data rate settings in WB-AMR networks, causing frequent spurious data rate changes in terminal devices.
Innovation Solution
A double-check mechanism involving a decoder, error detector, threshold generator, and comparator to determine the presence of data by comparing the actual decoder metric with a threshold value, reducing false alarms and improving data rate accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If blind transport format detection using CRC is implemented, then data detection capability is improved, but false alarm rate increases
Solution Approach 1:
The patent introduces an intermediary validation mechanism between the CRC check and the final data presence decision. The decoder metric (such as path metric in Viterbi decoding or log-likelihood ratio in turbo decoding) serves as an intermediary indicator that provides additional verification beyond the CRC check alone, thereby reducing false alarms while maintaining detection capability
Solution Approach 2:
The patent implements a feedback mechanism where the decoder metric value is fed back into the decision process. By comparing the actual decoder metric against a threshold derived from the maximum possible metric, the system creates a feedback loop that validates CRC results and suppresses false alarms through secondary verification
2Measurement precision
If CRC check strength is increased to reduce false alarms, then detection accuracy is improved, but computational complexity increases
Solution Approach 1:
The patent applies partial action by using the decoder metric as an additional validation layer only when needed (i.e., when CRC indicates data presence). This partial verification approach improves detection accuracy without fully implementing a completely redundant checking system, thereby balancing accuracy improvement with computational complexity constraints
Data Source
AI summary
The present invention relates to an apparatus and a method for detecting presence of data, wherein input data is decoded using a decoder metric to obtain decoded data, and an error check is performed for the decoded data. Furthermore, a threshold value is determined based on an obtained maximum value that the de coder metric can assume for the input data, and the threshold value is compared with an actual value of the decoder metric. Presence of the input data is then decided based on results of the error check and the comparison.