Downlink Control Channel Permutation Mapping for Blind Decoding Errors
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Solution Overview
Problem
In 3GPP LTE/LTE-A wireless communication systems, blind decoding errors in downlink control channels lead to significant reception errors between base stations and user equipment, affecting communication reliability.
Innovation Solution
A method and wireless device that decode and transmit downlink control information by mapping modulation symbols onto L resource units at an aggregation level greater than 1, using permutation and modulo-L mapping to prevent successful decoding at incorrect aggregation levels, thereby enhancing reception reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If blind decoding is used to detect PDCCH, then the downlink control channel can be detected without prior knowledge of aggregation level, but blind decoding errors occur leading to reception errors
Solution Approach 1:
The patent applies permutation mapping to rearrange modulation symbols in a deterministic pattern that creates distinct structural characteristics for each aggregation level. This allows the receiver to identify the correct aggregation level by detecting the permutation pattern, analogous to using color changes to distinguish different states. The permutation acts as a unique signature for each aggregation level, enabling reliable detection without blind decoding trials.
2Ease of manufacture
If modulation symbols are mapped directly to resource units without permutation, then mapping is simple, but blind decoding errors cannot be prevented at wrong aggregation levels
Solution Approach 1:
The patent applies permutation mapping as a preliminary transformation step before the actual resource unit assignment. By pre-arranging the modulation symbols in a specific permuted order, the system prepares the signal with embedded aggregation level identification information. This preliminary action ensures that when the signal is later decoded, the permutation pattern reveals the correct aggregation level, preventing errors without requiring complex real-time detection mechanisms.
3Productivity
If aggregation level L=1 is used, then resource usage is efficient, but reliability is reduced due to higher probability of blind decoding errors
Solution Approach 1:
The patent changes the mapping parameter by introducing permutation based on aggregation level. For L=1, the permutation creates a specific pattern that is distinctly different from L>1 patterns. This parameter change in the mapping structure allows the receiver to reliably distinguish L=1 from L>1 cases, enabling efficient use of single resource units while maintaining reliability through the unique permutation signature that prevents misinterpretation as higher aggregation levels.
Data Source
AI summary
Provided are a method for monitoring a control channel and a wireless device using same. A wireless device decodes downlink control information on a downlink control channel on L number of resource units in an aggregation level L (L>1). The downlink control information comprises a plurality of modulation symbols, and permutations of the plurality of modulation symbols are mapped to the L number of resource units.