PHICH Resource Allocation for LTE Cross-Carrier Scheduling
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Solution Overview
Problem
Current wireless communication systems, particularly in LTE technology, face challenges in efficiently allocating resources for Physical Hybrid Automatic Repeat Request (HARQ) Indicator Channel (PHICH) due to PHICH collisions during concurrent uplink transmissions, which affect HARQ response timing and resource availability, especially in cross-carrier scheduling scenarios with different UL/DL subframe configurations.
Innovation Solution
The proposed solution involves dynamic allocation and reconfiguration of PHICH resources, including doubling PHICH resources in specific subframes and using additional PDCCH resources to ensure proper HARQ response, while maintaining backward compatibility and flexibility in UL HARQ operations, by employing cross-scheduling techniques and re-mapping PHICH resources to avoid collisions and ensure timely HARQ responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PHICH resources are doubled in specific subframes to handle concurrent uplink transmissions, then PHICH collision is avoided and HARQ response reliability is improved, but resource overhead and system complexity increase
Solution Approach 1:
The patent implements dynamic PHICH resource allocation where the number of PHICH resources is adjusted based on the actual uplink transmission scenario. In subframes with concurrent uplink transmissions from multiple WTRUs, PHICH resources are doubled to prevent collisions. This dynamic adaptation resolves the contradiction by providing enhanced reliability only when needed, rather than maintaining high resources continuously, thus avoiding unnecessary complexity overhead.
Solution Approach 2:
The system changes the PHICH resource parameter (number of PHICH groups) based on the uplink transmission configuration. When cross-carrier scheduling is detected or concurrent uplink transmissions are identified, the PHICH resource parameter is modified to double the available resources. This parameter change enables the system to maintain reliability while managing complexity through conditional activation.
2Reliability
If additional PHICH resources are provisioned to prevent collisions during concurrent uplink transmissions, then HARQ response timing is improved, but resource overhead increases
Solution Approach 1:
The patent segments the PHICH resource allocation by subframe and by uplink transmission scenario. Instead of uniformly allocating additional PHICH resources across all subframes, the system selectively provisions extra resources only in subframes where concurrent uplink transmissions are detected or anticipated. This segmentation approach improves HARQ response timing for critical scenarios while minimizing overall resource overhead.
Solution Approach 2:
The system applies partial action by providing additional PHICH resources only when necessary for specific uplink transmission scenarios rather than always provisioning maximum resources. This selective approach ensures timely HARQ responses for concurrent transmissions while avoiding the waste of excessive resources in scenarios where standard PHICH allocation suffices.
3Reliability
If cross-carrier scheduling is implemented to coordinate PHICH resources across multiple carriers, then PHICH collision is reduced, but scheduling complexity and processing overhead increase
Solution Approach 1:
The patent implements cross-carrier scheduling mechanisms where a single scheduling entity coordinates PHICH resource allocation across multiple component carriers. This multi-functional approach allows the system to manage PHICH resources universally across carriers, reducing collisions by ensuring that uplink transmissions on different carriers do not simultaneously require the same PHICH resources. The complexity is managed through standardized scheduling procedures that apply across carriers.
Solution Approach 2:
The cross-carrier scheduling entity acts as an intermediary that coordinates between multiple carriers and their respective PHICH resources. This mediator ensures proper resource allocation by analyzing uplink transmission patterns across carriers and adjusting PHICH资源配置 accordingly, thereby reducing collisions while managing complexity through centralized coordination.
4Productivity
If PHICH resources are re-mapped to avoid collisions in cross-carrier scheduling scenarios, then resource utilization efficiency is improved, but configuration complexity and processing overhead increase
Solution Approach 1:
The patent implements preliminary PHICH resource mapping configurations that are pre-determined based on cross-carrier scheduling patterns. By establishing the re-mapping strategy in advance, the system avoids the need for complex real-time calculations during operation. The preliminary configuration ensures efficient resource utilization by pre-allocating PHICH resources to avoid collisions, while the complexity is managed through upfront planning rather than ongoing processing.
Data Source
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Figure 2
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AI summary
Certain aspects of the present disclosure relate to techniques for allocating resources for Physical Hybrid Automatic Repeat Request (HARQ) Indicator Channel (PHICH).