Downlink Control Channel Repetition Level Detection
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Solution Overview
Problem
Machine-type communication (MTC) devices in extended or enhanced coverage areas face challenges in receiving downlink channels due to repeated transmissions across multiple subframes, as they struggle to identify the number of repetitions of the downlink control channel, which hampers proper reception of the downlink data channel.
Innovation Solution
A method and device for receiving a downlink control channel in a wireless communication system, involving blind decoding using multiple scrambling codes, determining the repetition level based on successful decoding, and identifying the number of repetitions to determine the transmission resources for data channels and HARQ acknowledgments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the base station repeatedly transmits the same downlink control channel on multiple subframes to extend coverage, then the coverage area is improved, but the MTC device cannot identify the number of repetitions and cannot properly receive the downlink data channel
Solution Approach 1:
The patent uses different scrambling codes (analogous to color changes) for downlink control channels with different repetition numbers. The MTC device performs blind decoding with multiple scrambling codes and identifies the repetition number based on which scrambling code successfully decodes the channel, thereby recovering the lost repetition identification information while maintaining extended coverage
Solution Approach 2:
The patent changes the scrambling code parameter based on the repetition number. By mapping different repetition numbers to different scrambling codes, the system enables the MTC device to identify the repetition count through successful decoding attempts, solving the information loss problem while preserving the coverage extension benefit
2Reliability
If the MTC device performs blind decoding with multiple scrambling codes to identify repetition level, then the downlink data channel reception is improved, but the decoding complexity increases
Solution Approach 1:
The patent applies partial action by limiting the number of scrambling codes to be tested based on the maximum expected repetition number. Instead of exhaustive searching, the device performs blind decoding with a predefined set of scrambling codes corresponding to possible repetition levels, reducing complexity while maintaining reliable reception
Data Source
AI summary
The disclosure of the present specification provides a method for receiving a downlink control channel, which is repeated on a plurality of downlink subframes, by a wireless device in a wireless communication system. The method may comprise the steps of: attempting, by the wireless device, blind decoding of the downlink control channel, using one or more of multiple scrambling codes; when the blind decoding is successful, determining, by the wireless device, a repetition level for the downlink control channel on the basis of a scrambling code by which the wireless device has been successful in the blind decoding; and determining, by the wireless device, the number of repetitions of the downlink control channel according to the repetition level.