ACK/NACK Bundling Without DAI Bits for LTE-A Uplink
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Solution Overview
Problem
In LTE-Advanced systems, supporting ACK/NAK bundling on the PUCCH without DAI bits is challenging due to increased blind DCI decoding burden and additional system overhead, which affects uplink coverage and power saving.
Innovation Solution
Implementing non-DAI based solutions that reuse existing PDCCH design and mapping tables from Release 8 TDD, allowing eNB scheduling across multiple component carriers and using pre-defined CC numbering schemes to transmit bundled ACK/NAK/DTX based on the last correctly received PDCCH, without introducing additional overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DAI bits are introduced for ACK/NAK bundling on PUCCH, then scheduling flexibility and error detection capability are improved, but blind DCI decoding burden and system overhead increase
Solution Approach 1:
The patent extracts the essential function of DAI (downlink assignment index) from the DCI format by using the existing PDCCH reception count at the UE side. Instead of embedding DAI bits in DCI, the system utilizes the naturally occurring count of received PDCCH messages to determine bundling window size, thereby achieving error detection without increasing DCI overhead or blind decoding burden
Solution Approach 2:
The patent makes the existing PDCCH counting mechanism serve multiple functions: it simultaneously tracks the number of downlink assignments for HARQ-ACK bundling and provides implicit DAI functionality for error detection. This multi-functionality eliminates the need for separate DAI fields in DCI formats
2Reliability
If ACK/NAK bundling is implemented across multiple component carriers, then uplink coverage is optimized, but control channel complexity and resource management difficulty increase
Solution Approach 1:
The patent segments the multi-carrier ACK/NAK bundling problem into independent component carrier units, where each carrier's PDCCH reception is counted separately. The UE maintains separate counts for each component carrier and applies bundling independently per carrier, simplifying the overall control channel management while maintaining coverage benefits
Solution Approach 2:
The patent performs preliminary counting of PDCCH receptions at the UE side before transmitting HARQ-ACK feedback. By pre-calculating the bundling window size based on received PDCCH counts, the system prepares bundling parameters in advance, reducing real-time processing complexity during uplink transmission
3Adaptability or versatility
If Release 8 PUCCH resources are reserved for each component carrier, then backwards compatibility is maintained, but resource allocation overhead and scheduling flexibility are reduced
Solution Approach 1:
The patent merges the resource allocation for multiple component carriers into a unified PUCCH resource structure. Instead of maintaining separate reserved resources for each carrier, the system combines them into a single resource pool that serves all carriers, reducing overhead while maintaining compatibility with Release 8 terminal expectations through standardized resource indexing
Data Source
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AI summary
There is provided a method comprising: performing (1301) frequency domain acknowledgement/negative acknowledgement (ACK/NAK) bundling across component carriers within a user equipment reception bandwidth; generating (1302) a bundled ACK/NAK value corresponding to at least one code word on the basis of the performed ACK/NAK bundling; and including (1303) information relating to the generated bundled ACK/NAK value and the number of detected downlink grants within the user equipment reception bandwidth in an ACK/NAK resource to be transmitted on an uplink control channel.