HARQ Acknowledgement Encoding for Multi-Carrier LTE Overhead
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Solution Overview
Problem
In 3GPP LTE compliant communications systems, ACK/NACK control signaling consumes significant overhead, particularly with higher bandwidth deployments, negatively impacting system performance.
Innovation Solution
A method and system for transmitting and receiving acknowledgement information by determining HARQ responses for each component carrier, generating an information vector, encoding it, and assigning a fixed vector value to undetected transmissions, utilizing a priori information to improve decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACK/NACK control signaling is transmitted for each component carrier, then HARQ feedback reliability is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts and removes the redundant DTX state reporting for component carriers where no transmission was detected. By taking out the unnecessary ACK/NACK signaling for carriers without transmissions, the system reduces overhead while maintaining reliability for actual transmissions.
Solution Approach 2:
Instead of transmitting ACK/NACK for all configured component carriers, the patent inverts the approach by only transmitting ACK/NACK for component carriers where transmissions were actually detected. The DTX state is implicitly understood when no ACK/NACK is transmitted for a detected carrier.
2Measurement precision
If DTX state is explicitly fed back for all component carriers, then transmission detection accuracy is improved, but system complexity increases
Solution Approach 1:
The patent applies local quality by treating different component carriers differently based on transmission detection results. For carriers with detected transmissions, explicit ACK/NACK feedback is provided; for carriers without detected transmissions, DTX is implicitly indicated by absence of feedback, reducing overall system complexity.
Solution Approach 2:
The patent performs preliminary action by having the UE detect PDCCH transmissions before generating ACK/NACK feedback. This preliminary detection step allows the system to determine which component carriers require explicit feedback and which can be implicitly indicated as DTX, simplifying the overall feedback mechanism.
3Loss of information
If ACK/NACK information is transmitted for every configured component carrier, then feedback completeness is improved, but resource utilization decreases
Solution Approach 1:
The patent applies partial action by transmitting ACK/NACK feedback only for the subset of component carriers where transmissions were actually detected, rather than for all configured component carriers. This partial feedback approach maintains necessary information while improving resource utilization by reducing unnecessary signaling.
Solution Approach 2:
The patent converts the potential harm of incomplete feedback (by not transmitting ACK/NACK for all carriers) into a benefit by using implicit DTX indication. The absence of ACK/NACK transmission itself becomes the signal for DTX state, maintaining feedback completeness while reducing overhead.
Data Source
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AI summary
A system and method for transmitting and receiving acknowledgement information are provided.A method for communication device operations includes: determining a hybrid automatic repeat request (HARQ) response for each component carrier (CC) in a set of configured CCs,thereby producing a set of HARQ responses,generating an information vector from the set of HARQ responses,encoding the information vector,and transmitting the encoded information vector.A sub-vector of one or more bits selected from the information vector is assigned a fixed vector value independent of HARQ responses for CCs not in a set of CCs when the set of CCs is not empty,wherein the set of CCs comprises at least one CC whose HARQ response is equal to Discontinuous Transmission (DTX).