HARQ-ACK Transmission in Traffic Adaptive TDD Systems
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Solution Overview
Problem
In the LTE TDD system, newer UEs and older UEs coexist, leading to compatibility issues and wastage of PUCCH resources due to different TDD uplink and downlink configurations, where newer UEs transmit HARQ-ACK feedback information based on reference configurations, while older UEs follow configurations indicated by system information, resulting in inefficient use of PUCCH resources.
Innovation Solution
A method and apparatus for transmitting HARQ-ACK feedback information in a traffic adaptive TDD system, where a UE receives System Information Block (SIB) to identify TDD uplink and downlink configurations, determines implicit PUCCH resources, and transmits HARQ-ACK feedback using specific PUCCH formats based on the obtained HARQ-ACK timing, ensuring compatibility with older UEs and optimizing resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If newer UEs transmit HARQ-ACK based on reference TDD configurations while older UEs follow configurations from system information, then compatibility between different UE types is maintained, but PUCCH resources are wasted due to mismatched allocations
Solution Approach 1:
The patent applies dynamics by enabling the TDD uplink-downlink configuration to change dynamically based on actual traffic conditions. The base station can adjust the configuration from a reference configuration to an actual configuration that matches current traffic patterns, allowing the system to adapt between different operational states while maintaining backward compatibility with older UEs through the reference configuration mechanism.
Solution Approach 2:
The patent utilizes parameter changes by modifying the TDD configuration parameters (specifically the uplink-downlink subframe assignment) to optimize resource allocation. When traffic patterns change, the system changes the configuration parameters to match actual needs, thereby eliminating the waste of PUCCH resources that occurs when static reference configurations are used.
2Ease of operation
If TDD uplink and downlink configuration is fixed according to reference configuration, then HARQ-ACK timing is simplified for newer UEs, but resource allocation becomes inefficient when actual traffic patterns differ from reference
Solution Approach 1:
The system transitions from a static reference configuration to a dynamic configuration that adapts to actual traffic conditions. The base station determines both a reference configuration (for backward compatibility and simplified timing) and an actual configuration (for optimal resource allocation), allowing the system to maintain ease of operation while improving productivity through traffic-adaptive resource allocation.
Solution Approach 2:
The patent introduces an intermediary mechanism where the base station maintains both reference configuration information and actual configuration information. This intermediary approach allows newer UEs to benefit from simplified HARQ-ACK timing based on reference configuration while the system simultaneously optimizes resource allocation using actual traffic-based configuration, resolving the contradiction between simplicity and efficiency.
3Reliability
If PUCCH resources are allocated based on reference TDD configuration, then older UEs can operate correctly, but newer UEs experience resource waste when actual configuration differs from reference
Solution Approach 1:
The patent segments the TDD configuration into two distinct parts: reference configuration (for backward compatibility with older UEs) and actual configuration (for optimal resource allocation with newer UEs). This segmentation allows the system to maintain reliability for older UEs by preserving their expected behavior while eliminating resource waste for newer UEs through traffic-adaptive actual configuration.
Solution Approach 2:
The reference configuration serves multiple functions: it ensures backward compatibility with older UEs, provides a baseline for HARQ-ACK timing calculations, and acts as a fallback when actual configuration cannot be determined. This multi-functionality maintains reliability across different UE types while the actual configuration optimizes resource allocation for newer UEs.
Data Source
AI summary
A method and an apparatus are provided for HARQ-ACK feedback information transmission in a traffic adaptive TDD system. The method includes receiving, by a User Equipment (UE), a System Information Block (SIB); obtaining, by the UE, a TDD uplink and downlink configuration that is indicated by current system information and does not support traffic adaptive UE, from the SIB; identifying, by the UE, implicit resources of Physical Uplink Control Channel (PUCCH) based on the TDD uplink and downlink configuration; obtaining, by the UE, a HARQ-ACK timing that supports a traffic adaptive UE; and transmitting, by the UE, the HARQ-ACK feedback information on determined PUCCH resources using a determined PUCCH format, based on the obtained HARQ-ACK timing.