HARQ Feedback Handling in LTE UL/DL Configuration Conflicts
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Solution Overview
Problem
In LTE/LTE-A systems, conflicts arise when advanced UEs and legacy UEs have different UL/DL configurations, leading to issues in receiving HARQ feedback, as existing technologies do not provide a method to handle these conflicts effectively.
Innovation Solution
A method and communication device that detect and handle HARQ feedback by determining its presence in PHICH or ePHICH based on the UL/DL configurations of both advanced and legacy UEs, allowing the advanced UE to change configurations quickly while ensuring the legacy UE can still detect HARQ feedback, by arranging HARQ feedback in PHICH or ePHICH resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the advanced UE changes UL/DL configuration rapidly to match fast varying traffic characteristics, then the system can improve adaptability and performance, but conflicts arise with legacy UEs that cannot change configurations frequently, leading to HARQ feedback reception failures
Solution Approach 1:
The patent segments the PHICH resources into two distinct sets: a first set of PHICH resources configured according to the legacy UE's UL/DL configuration, and a second set of PHICH resources configured according to the advanced UE's UL/DL configuration. This segmentation allows each UE type to access its designated PHICH resources without interference, resolving the conflict between rapid configuration changes and reliable HARQ feedback reception.
Solution Approach 2:
The patent introduces a UE type indicator in the ePHICH as an intermediary mechanism that enables the advanced UE to identify and select the appropriate PHICH resource set. This intermediary signal allows the advanced UE to distinguish between the first PHICH resources (for legacy UEs) and the second PHICH resources (for advanced UEs), ensuring correct HARQ feedback reception despite configuration differences.
2Ease of operation
If the eNB schedules legacy UEs to avoid subframes with different transmission directions due to configuration differences, then legacy UE compatibility is maintained, but the advanced UE loses access to certain subframes for HARQ feedback reception
Solution Approach 1:
The patent divides the PHICH resources into separate sets that can be independently configured and accessed. The first set serves legacy UEs with fixed UL/DL configurations, while the second set serves advanced UEs with dynamically configured UL/DL patterns. This segmentation eliminates the need for the eNB to avoid scheduling legacy UEs in specific subframes, as each UE type can access its designated resources regardless of subframe configuration.
Solution Approach 2:
The ePHICH structure with UE type indicator provides universal functionality by supporting both legacy and advanced UE types within the same system. The advanced UE can use the ePHICH to receive HARQ feedback in subframes that would traditionally be unavailable, while legacy UEs continue to operate with their existing PHICH configuration, achieving multi-functionality without sacrificing either UE type's performance.
3Productivity
If the number of PHICH groups is increased to accommodate advanced UE requirements, then advanced UE performance is improved, but legacy UEs cannot properly detect PHICH resources due to configuration mismatches
Solution Approach 1:
The patent segments PHICH resources into a first set for legacy UEs and a second set for advanced UEs. The first set maintains the traditional PHICH group configuration that legacy UEs can detect using their existing UL/DL configuration. The second set provides additional PHICH groups for advanced UEs with higher configuration flexibility. This segmentation ensures that increasing the total number of PHICH groups does not harm legacy UE detection capability, as their designated resources remain unchanged.
Solution Approach 2:
The patent applies local quality by configuring different PHICH resource sets with different properties suitable for different UE types. The first PHICH resources are configured with parameters optimized for legacy UE detection, while the second PHICH resources are configured for advanced UE requirements. This local differentiation allows each UE type to access optimally configured resources without affecting the other.
Data Source
AI summary
A method of handling a hybrid automatic repeat request (HARQ) feedback in a subframe for a first communication device in a wireless communication system is disclosed. The method comprises determining whether the HARQ feedback exists in a physical HARQ indicator channel (PHICH) in a downlink (DL) control region of the subframe transmitted by a network of the wireless communication system according to a first uplink (UL)/DL configuration of the first communication device and a second UL/DL configuration of a second communication device in the wireless communication system communicating with the network; detecting the HARQ feedback in the PHICH of the subframe, if the HARQ feedback exists in the PHICH; and detecting the HARQ feedback in an enhanced PHICH (ePHICH) of the subframe, if the HARQ feedback does not exist in the PHICH.