Handling Inconsistent Control Information in Wireless Systems
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Solution Overview
Problem
Wireless communication systems face challenges in handling inconsistent control information, particularly in LTE systems, where multiple PDCCH grants for the same transport block may indicate different transport block sizes, leading to decoding errors and inconsistent data transmission parameters.
Innovation Solution
User Equipment (UE) employs different strategies to handle inconsistent control information based on whether the grants are for downlink or uplink transmissions, retaining or discarding grants accordingly to maintain data transmission reliability, and using the most recent or initial grant to determine transport block sizes for downlink and uplink respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE receives multiple grants with different transport block sizes for the same transport block, then the system can adapt to varying data transmission requirements, but decoding errors occur due to inconsistent control information
Solution Approach 1:
The patent inverts the conventional approach by having the UE compare subsequent grants against the most recent grant for downlink transmissions (rather than the initial grant), and against the initial grant for uplink transmissions. This inversion resolves the contradiction by adapting the comparison reference point to the specific transmission direction, allowing transport block size adaptation while preventing decoding errors through direction-appropriate consistency checks.
Solution Approach 2:
The patent applies different handling strategies for downlink and uplink grants based on their local characteristics. For downlink, the UE compares against the most recent grant to allow flexibility; for uplink, the UE compares against the initial grant to ensure consistency. This local quality approach resolves the contradiction by tailoring the inconsistency detection mechanism to the specific requirements of each transmission direction.
2Adaptability or versatility
If the UE retains the second grant with inconsistent control information, then data transmission flexibility is improved, but data integrity deteriorates due to potential decoding errors
Solution Approach 1:
The patent makes the grant retention decision dynamic by adjusting the inconsistency detection reference based on transmission direction. For downlink, the UE dynamically compares against the most recent grant, allowing retention of grants with different transport block sizes. For uplink, the UE compares against the initial grant, discarding inconsistent grants to preserve data integrity. This dynamic approach resolves the contradiction between flexibility and integrity.
Solution Approach 2:
The patent changes the parameter used for inconsistency detection based on the transmission direction. The reference grant (most recent vs. initial) is changed according to whether the transmission is downlink or uplink. This parameter change allows the system to retain grants with different transport block sizes for downlink while maintaining strict consistency for uplink, resolving the contradiction between flexibility and integrity.
3Reliability
If the UE compares subsequent grants against the initial grant for all transmissions, then consistency is maintained, but adaptability to changing transmission requirements is reduced
Solution Approach 1:
The patent segments the inconsistency detection process into two distinct paths: one for downlink transmissions (comparing against most recent grant) and one for uplink transmissions (comparing against initial grant). This segmentation resolves the contradiction by allowing transport block size variation for downlink while maintaining consistency for uplink, rather than applying a single rigid comparison rule to all transmissions.
Solution Approach 2:
The patent makes the comparison reference dynamic rather than static. Instead of always comparing against the initial grant, the reference changes based on transmission direction and timing. For downlink, the reference is the most recent grant; for uplink, it's the initial grant. This dynamic approach enables both consistency and adaptability in different contexts.
Data Source
AI summary
Techniques for handling inconsistent control information in a wireless communication system are described. In an aspect, inconsistent control information is handled in different manners for the downlink and uplink. In one design, a user equipment (UE) receives a first grant with first control information for a first data transmission and also receives a second grant with second control information for a second data transmission. The UE determines that the second control information is inconsistent with the first control information, e.g., due to the two grants conveying different transport block sizes. The UE determines whether to retain or discard the second grant based on whether the two grants are for data transmissions on the downlink or uplink. In one design, the UE retains the second grant if the two grants are for data transmissions on the downlink and discards the second grant if the two grants are for data transmissions on the uplink.