Feedback Information Packaging Using DAI Ordering
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Solution Overview
Problem
In 3GPP LTE systems, the existing Physical Uplink Control Channel (PUCCH) design faces challenges in packaging information bits, particularly in determining feedback package length and ordering, especially with the increase in the number of Component Carriers (CCs), leading to ambiguity and decoding errors due to missing Downlink Control Information (DCI) grants.
Innovation Solution
The proposed solution involves using Downlink Assignment Index (DAI) ordering to determine the codebook size for feedback information bits, with explicit or implicit signaling of codebook partitions, allowing the User Equipment (UE) to accurately encode and transmit HARQ-ACK bits by identifying missed assignments and selecting the appropriate codebook size, thereby reducing ambiguity and improving decoding accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of Component Carriers is increased to support higher data rates and system capacity, then the peak data rates and system capacity are improved, but the uplink control channel capacity becomes a limitation and ambiguity arises in determining feedback package length
Solution Approach 1:
The patent segments the feedback information into discrete codebooks with predefined sizes. By dividing the feedback package into structured codebooks (e.g., codebook size 4, 8, 16, 32), the system can efficiently manage the uplink control channel capacity even when supporting up to 32 Component Carriers. This segmentation allows the UE to select an appropriate codebook size based on the number of scheduled CCs, preventing control channel overload while maintaining high data rates.
2Productivity
If the feedback package length is dynamically determined based on the number of scheduled Component Carriers, then the uplink control channel efficiency is improved, but ambiguity and decoding errors occur due to missing Downlink Control Information grants
Solution Approach 1:
The patent establishes preliminary rules for determining feedback package length before actual transmission occurs. The UE is configured with predefined codebook sizes and selection criteria that are determined in advance based on the number of scheduled Component Carriers. This preliminary determination mechanism eliminates ambiguity at transmission time, as both the UE and eNodeB can independently calculate the expected feedback package length using the same pre-agreed rules, even if some DCI grants are missed.
Solution Approach 2:
The patent changes the parameter of feedback package length from a dynamic value subject to ambiguity to a selected value from a discrete set of predefined codebook sizes. By mapping the number of scheduled CCs to specific codebook sizes (e.g., 4-8 CCs maps to codebook size 16), the system transforms a potentially ambiguous parameter into a deterministic one, ensuring reliable decoding at the eNodeB side.
3Quantity of substance
If a new PUCCH format is designed to support larger payload size for 32 downlink CCs, then the feedback capacity is improved, but the device complexity and standardization effort increase
Solution Approach 1:
The patent makes the existing PUCCH format multi-functional by enabling it to carry different codebook sizes (4, 8, 16, 32) through dynamic codebook selection rather than requiring separate PUCCH formats for each payload size. The same PUCCH resource can accommodate feedback for any number of Component Carriers by selecting the appropriate codebook size, eliminating the need for complex new PUCCH format designs and reducing overall system complexity.
Data Source
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AI summary
The present disclosure relates to packaging of feedback information bits in a wireless communication system. Some embodiments are applicable to both Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD) systems, whereas other embodiments are particularly well-suited for TDD systems. In some embodiments, a method of operation of a wireless device in a cellular communications network comprises receiving, from the cellular communications network, an indication of one of a plurality of predefined sets of feedback information codebook sizes, the plurality of predefined sets of feedback information codebook sizes being disjoint subsets of a plurality of predefined feedback information codebook sizes. In some embodiments, the indication enables the wireless device to return an expected number of feedback information bits to the cellular communications network, particularly in a saturation where the wireless device misses one or more downlink assignments.