Receiver Decoding Control via Channel Quality Measurement
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Solution Overview
Problem
In poor communication environments, wireless communication devices face a low decoding success rate due to inadequate channel quality, particularly in LTE systems, where the decoding performance of the physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH) is limited by the decoding success rate of the physical control format indicator channel (PCFICH).
Innovation Solution
A receiver apparatus and method that measures channel quality and decodes downlink control indicators (DCI) by decoding physical downlink control channel (PDCCH) areas corresponding to each channel format indicator (CFI), with the ability to obtain CFI from the physical control format indicator channel (PCFICH) when channel quality conditions are met, and decodes PDCCH for available CFI values to enhance decoding success rates even in error-prone environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the receiver decodes PDCCH based on CFI obtained from PCFICH, then the decoding process is simple and fast, but the decoding success rate deteriorates in poor channel quality
Solution Approach 1:
The receiver performs preliminary blind decoding of PDCCH for multiple possible CFI values (1, 2, 3, 4) before final determination. This preliminary action allows the system to prepare multiple decoding candidates in advance, so when channel quality is poor and PCFICH decoding fails, the receiver already has alternative decoded results to fall back on, thereby improving decoding success rate without significantly impacting overall decoding speed.
Solution Approach 2:
The invention changes the parameter of CFI from a single fixed value (obtained from PCFICH) to multiple possible values (1, 2, 3, 4) that are tested through blind decoding. By varying the CFI parameter across multiple possibilities and selecting the most reliable decoded result, the system adapts to poor channel conditions where the original CFI from PCFICH may be erroneous, thus improving reliability while maintaining acceptable productivity.
2Reliability
If the receiver decodes PDCCH for multiple CFI values, then the decoding success rate improves, but the device complexity increases
Solution Approach 1:
The decoding process is segmented into distinct stages: first decoding PDCCH for multiple CFI values (1, 2, 3, 4) separately, then evaluating the reliability of each decoded result, and finally selecting the most reliable one. This segmentation allows the complex task of multi-CFI decoding to be broken down into manageable, independent decoding operations followed by a selection process, making the overall complexity more tractable while maintaining high decoding success rates.
Solution Approach 2:
The system incorporates feedback mechanisms by evaluating the reliability of each PDCCH decoding result (e.g., through CRC checks or signal quality metrics) and using this feedback to select the most reliable decoded CFI value. This feedback-driven selection process ensures that the receiver chooses the correct CFI even when multiple decoding attempts are made, improving reliability without requiring the system to permanently maintain all decoding paths, thus controlling device complexity.
3Ease of operation
If the receiver relies on PCFICH decoding to obtain CFI, then the system operation is simple, but the reliability deteriorates when channel quality is poor
Solution Approach 1:
The invention introduces an intermediary blind decoding process that acts as a mediator between the simple PCFICH-based CFI acquisition and the reliable PDCCH decoding. Instead of directly relying on PCFICH output, the system uses blind decoding of PDCCH for multiple CFI values as an intermediary step to verify and select the correct CFI. This intermediary mechanism maintains operational simplicity by following standard protocols while significantly improving CFI acquisition reliability in poor channel conditions.
Data Source
AI summary
A method and an apparatus are provided for determining a downlink control indicator (DCI) at a receiver. A signal is received at the receiver. The receiver measures channel quality based on the received signal. Signals of physical downlink control channel (PDCCH) areas that correspond to each channel format indicator (CFI) in the received signal are decoded, if a measurement of the channel quality is not a configuration condition. The receiver obtains the CFI by decoding a physical control format indicator channel (PCFICH) of the received signal, if the measurement of the channel quality is the configuration condition. The receiver determines the DCI based on the decoded signals.