HARQ Feedback Encoding for Multi-Carrier ACK/NACK Overhead
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Solution Overview
Problem
In wireless communications systems, especially 3GPP LTE compliant systems, ACK/NACK control signaling consumes a significant amount of overhead, particularly in higher bandwidth deployments, negatively impacting overall 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 value to bits corresponding to DTX responses, thereby optimizing ACK/NACK information encoding and decoding to reduce overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ACK/NACK control signaling is transmitted for each component carrier in higher bandwidth deployments, then data transmission capacity is improved, but control signaling overhead increases and negatively impacts system performance
Solution Approach 1:
The patent segments the ACK/NACK feedback mechanism by introducing a DTX state that allows the UE to indicate no transmission detected without requiring full ACK/NACK signaling for all component carriers. This segmentation reduces the quantity of control signaling needed while maintaining the ability to support multiple component carriers for high data transmission capacity
Solution Approach 2:
Instead of requiring complete ACK/NACK feedback for all component carriers, the patent applies partial action by allowing the UE to transmit only a DTX indicator when no transmission is detected on any component carrier. This reduces control signaling overhead while still enabling the system to operate with multiple component carriers for high productivity
2Loss of information
If DTX state is fed back by transmitting nothing on PUCCH, then the UE can indicate no transmission detected, but the eNB cannot distinguish between no PDCCH for the UE and PDCCH detection failure
Solution Approach 1:
The patent introduces an intermediary mechanism where the UE transmits a specific DTX indicator signal on the PUCCH when no transmission is detected. This intermediary signal serves as a mediator between the UE's DTX state and the eNB's interpretation, allowing the eNB to reliably distinguish DTX from other states without requiring the UE to transmit nothing, thereby improving both information loss prevention and detection accuracy
3Productivity
If multiple channels are multiplexed over a single set of physical channel resources, then network resource utilization is improved, but control signaling and data interfere with each other
Solution Approach 1:
The patent extracts the DTX indication from the traditional ACK/NACK feedback mechanism and creates a separate, simplified signaling path. By taking out the DTX state handling from the main ACK/NACK signaling flow, the patent reduces control signaling interference while maintaining efficient multiplexing of multiple channels over physical resources, as the DTX indicator is more compact and requires fewer resources
Data Source
AI summary
A system and method for transmitting and receiving acknowledgement information are provided. A method for communications device operations includes determining a hybrid automatic repeat request (HARQ) response for each component carrier (CC) in a set of CCs configured by higher layer signaling, 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. The information vector comprises one or more bits respectively corresponding to a CC in the set of CCs. A bit is assigned a fixed value if HARQ response of a corresponding CC is set to DTX in response to no transmission detected over the CC.