Radio Link Problem Detection Using Hypothetical Control Channels
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Solution Overview
Problem
Existing wireless communication systems face inaccuracies and testability issues in detecting radio link problems and recoveries due to inadequate metrics, particularly in low signal-to-interference and noise ratios, leading to performance degradation.
Innovation Solution
Combining hypothetical physical control format indicator channel (PCFICH) and physical downlink control channel (PDCCH) transmissions with two-step exponential effective SINR mapping to estimate error rates, which are then averaged and compared against thresholds for accurate radio link problem and recovery detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If using PCFICH and pseudo-error rate based on received symbols to detect RLP/RLR, then the detection method is simple to implement, but the accuracy deteriorates due to absence of error detection code and small number of subcarriers
Solution Approach 1:
The patent introduces hypothetical PCFICH and PDCCH transmissions as intermediary constructs that enable accurate error rate estimation without requiring actual transmissions. These hypothetical channels serve as mediators between the received signal and the error detection mechanism, allowing CRC-based accuracy while maintaining implementation feasibility through standardized mapping procedures.
Solution Approach 2:
The patent creates copies of the control channel structure (PCFICH and PDCCH) in the form of hypothetical transmissions. These copies replicate the channel characteristics and error patterns of actual transmissions, enabling accurate error rate measurement through simulated decoding processes that mirror real-world performance without requiring additional physical transmission resources.
2Reliability
If using combination of actual PCFICH and actual PDCCH to detect radio link failure, then the detection uses real transmissions, but the accuracy deteriorates because UE cannot distinguish between true decoding error and absence of PDCCH grant
Solution Approach 1:
The patent inverts the traditional detection approach by not relying on actual PDCCH grants to validate decoding accuracy. Instead, it uses hypothetical PDCCH transmissions with known structure to create a controlled environment where decoding errors can be unambiguously identified through CRC checks, separating the detection function from the grant allocation function.
Solution Approach 2:
The hypothetical PDCCH transmission acts as an intermediary that provides a controlled reference for error detection. By introducing this intermediary channel with known characteristics and structure, the system can accurately measure decoding performance without the confounding factor of variable PDCCH grant availability in actual transmissions.
3Measurement precision
If using hypothetical PDCCH transmission to map to estimated BLER for RLF detection, then the accuracy improves, but the feasibility for conformance testing deteriorates as PDCCH error rate is not observable without PCFICH errors
Solution Approach 1:
The patent segments the control channel detection into distinct measurable components: hypothetical PCFICH transmission, hypothetical PDCCH transmission, and their respective error rates. This segmentation allows independent measurement and validation of each component's performance, making conformance testing feasible by allowing verification of individual segment accuracy without requiring observation of dependent variables.
Solution Approach 2:
The patent performs preliminary actions by establishing the hypothetical transmission models and error rate calculation methods before actual conformance testing. By pre-defining the mapping relationships and measurement procedures for hypothetical channels, the system enables straightforward validation during testing without needing to observe complex interactions between actual and hypothetical transmissions.
4Measurement precision
If using third approach with hypothetical PDCCH transmission, then the accuracy improves in overcoming shortcomings of previous approaches, but the reliability in low SINR environments deteriorates due to overly optimistic results
Solution Approach 1:
The patent applies parameter changes by using two-step exponential effective SINR mapping that transforms received signal quality metrics into accurate error rate estimates. This parameter transformation adjusts the measurement scale to reflect actual decoding performance in low SINR conditions, preventing overly optimistic results by properly accounting for signal degradation effects on both PCFICH and PDCCH channels.
Data Source
AI summary
A technique for radio link detection in a wireless communication system includes estimating a first error rate of an indicator channel. In this case, the indicator channel includes an indication of a number of symbols in a control channel. A second error rate of the control channel is also estimated. The first and second error rates are then combined to provide a performance metric. Based on the performance metric, a determination is made as to whether a radio link problem exists.