Redundancy Version Grouping for Coherent Combination in MTC Retransmissions
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Solution Overview
Problem
In current communication technologies, during retransmissions in Machine Type Communications (MTC), the varying redundancy versions across subframes prevent coherent combination of signals, leading to a decrease in system spectral efficiency.
Innovation Solution
The method determines identical redundancy versions for consecutive subframes within a repetition time period, allowing for coherent combination of information transmitted, and enables incremental redundancy combination by varying redundancy versions across the entire period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundancy versions vary across subframes during repeated transmission, then the transmission diversity is improved, but coherent combination cannot be performed and system spectral efficiency decreases
Solution Approach 1:
The repetition time period is divided into multiple groups, where each group contains multiple consecutive subframes. Within each group, the same redundancy version is used for all subframes, enabling coherent combination. Different groups can use different redundancy versions, maintaining transmission diversity. This segmentation resolves the contradiction by organizing subframes into structured groups with controlled redundancy version patterns.
Solution Approach 2:
Different redundancy version strategies are applied to different local regions (groups) within the repetition time period. Each group maintains a uniform redundancy version for coherent combination, while different groups may use different redundancy versions. This local quality approach allows simultaneous achievement of coherent combination within groups and diversity across groups.
2Productivity
If redundancy versions are kept identical across all subframes, then coherent combination can be performed, but transmission diversity is reduced
Solution Approach 1:
The repetition time period is segmented into multiple groups, each with uniform redundancy versions enabling coherent combination. Different groups use different redundancy versions, restoring transmission diversity at the group level. This segmentation allows both coherent combination (within groups) and diversity (across groups) to coexist.
Solution Approach 2:
Redundancy versions are applied in a periodic pattern across groups within the repetition time period. Each group follows a periodic structure with consistent redundancy versions, enabling coherent combination. The periodic variation across groups maintains diversity, resolving the contradiction between coherent combination and transmission diversity.
3Productivity
If retransmission times are reduced to prevent spectral efficiency decrease, then system spectral efficiency is improved, but coverage enhancement capability is reduced
Solution Approach 1:
The patent enables continuous useful action by allowing coherent combination across multiple subframes within groups. This continuous combination process effectively increases the signal strength and reliability without requiring additional retransmissions, thereby maintaining spectral efficiency while achieving coverage enhancement.
Solution Approach 2:
The patent merges signals from multiple subframes within each group through coherent combination. This merging process accumulates signal energy and improves reception reliability, enabling coverage enhancement without increasing the number of separate retransmission events, thus preserving spectral efficiency.
Data Source
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AI summary
An information transmission method and an information transmission device are provided, so as to determine redundancy versions corresponding to a plurality of consecutive subframes as an identical redundancy version, thereby to enable identical information to be transmitted within the plurality of consecutive subframes after a rate matching and enable an opposite end to perform coherent combination on the information transmitted within the plurality of consecutive subframes. The information transmission method includes steps of: determining, by a local end serving as a transmitting end, information to be repeatedly transmitted within a repetition time period containing a plurality of subframes; and determining, by the local end, a redundancy version corresponding to each subframe in the repetition time period, performing a rate matching on a bit stream acquired by encoding the information based on the redundancy version corresponding to the subframe, and transmitting the bit stream processed through the rate matching to an opposite end, where a plurality of consecutive subframes among the subframes in the repetition time period corresponds to an identical redundancy version.