HARQ-ACK Coding in TDD Carrier Aggregation
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Solution Overview
Problem
Current wireless communication systems face inefficiencies in transmitting acknowledgement information in uplink channels, particularly in Time Division Duplex (TDD) systems, leading to unnecessary retransmissions and reduced throughput due to HARQ-ACK bundling and limited reliability in HARQ-ACK payload transmission.
Innovation Solution
A method for encoding acknowledgement information bits by a user equipment (UE) in a TDD communication system, where bits are generated and encoded based on the number of subframes and cells, using alternating codes for excess bits, and applying spatial-domain bundling, time-domain bundling, or cell-domain bundling to reduce the HARQ-ACK payload to manageable levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If HARQ-ACK bundling is applied to reduce payload size, then the complexity of transmission is reduced, but reliability deteriorates due to unnecessary retransmissions
Solution Approach 1:
The patent segments the HARQ-ACK payload into multiple codeblocks (CBs) for independent encoding and transmission. Instead of treating the entire payload as a single unit, each codeblock is separately processed through channel coding, allowing selective retransmission of only failed segments rather than the entire payload, thus improving reliability while managing complexity.
Solution Approach 2:
The patent dynamically adjusts coding parameters including code rate, codeblock size, and modulation scheme based on channel conditions and payload characteristics. By changing these parameters adaptively, the system optimizes the balance between transmission reliability and resource efficiency, avoiding unnecessary retransmissions while maintaining manageable complexity.
2Reliability
If channel coding is applied to improve reliability, then transmission reliability is improved, but overhead increases reducing throughput
Solution Approach 1:
The patent applies partial coding by dividing the payload into codeblocks and applying coding only to necessary segments. Not all codeblocks require full retransmission - successful ones can be discarded while only failed codeblocks are retransmitted, reducing the effective overhead compared to traditional all-or-nothing coding approaches.
Solution Approach 2:
The patent implements dynamic coding where coding parameters such as code rate and codeblock size are adjusted based on channel conditions, payload size, and traffic requirements. This dynamic adaptation allows the system to optimize the trade-off between reliability improvement and throughput maintenance, applying stronger coding only when necessary.
3Quantity of substance
If multiple codeblocks are used to handle large payloads, then capacity is improved, but device complexity increases
Solution Approach 1:
The patent segments large HARQ-ACK payloads into multiple manageable codeblocks, each with standardized encoding procedures. This segmentation allows the system to handle large payloads by breaking them into smaller units that can be processed independently using the same encoding algorithms, preventing exponential complexity growth with payload size.
Solution Approach 2:
The patent optimizes codeblock parameters such as size and number based on payload characteristics and channel conditions. By dynamically adjusting these parameters, the system maintains efficient processing complexity while accommodating varying payload capacities, avoiding the need for overly complex encoding schemes for all payload sizes.
4Device complexity
If spatial-domain bundling is applied to reduce bits, then payload size is reduced, but information loss increases
Solution Approach 1:
The patent segments spatial-domain bundling operations to apply bundling at appropriate granularities rather than uniformly across all spatial layers. By selectively applying bundling to specific codeblocks or spatial layers based on their characteristics, the system reduces payload size while preserving critical ACK information that would otherwise be lost through aggressive bundling.
Data Source
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AI summary
Methods and apparatus are provided for a User Equipment (UE) configured with multiple cells in a DownLink (DL) of a Time Division Duplex (TDD) communication system to determine the coding method for acknowledgement information bits as a function of their number, to apply bundling to the acknowledgement information bits when their number exceeds a first predetermined value, and to partition the acknowledgement information bits, possibly together with other control information bits, into two separate codewords when their total number exceeds a second predetermined value.