PHICH Resource Allocation for Multiple Uplink Carriers
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Solution Overview
Problem
Existing physical layer acknowledgement schemes in LTE Release 8 are inadequate to handle multiple uplink component carriers, as they can only acknowledge data signaling from a single carrier, leading to insufficient PHICH resources for additional component carriers.
Innovation Solution
The solution involves reallocating control channel elements (CCEs) from PDCCH signaling to support additional PHICH signaling for multiple uplink shared channel transmissions, allowing a single downlink carrier to acknowledge multiple uplink component carriers or spatial channels by mapping CCEs for PHICH signaling, while maintaining compatibility with legacy systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing PHICH resources from LTE Release 8 are used, then compatibility with legacy systems is maintained, but the resources are insufficient to acknowledge multiple uplink component carriers
Solution Approach 1:
The patent applies multi-functionality by enabling CCEs to serve dual purposes: traditional PDCCH signaling and additional PHICH signaling for multiple uplink carriers. This allows the system to maintain legacy compatibility while extending support to carrier aggregation scenarios, resolving the contradiction between versatility and resource quantity.
Solution Approach 2:
The patent extends the PHICH resource dimension by utilizing CCEs (which were previously only for PDCCH) to provide additional PHICH resources. This dimensional expansion allows acknowledgment of multiple uplink carriers without increasing the traditional PHICH resource pool, thus resolving the resource insufficiency issue.
2Quantity of substance
If CCEs are reallocated from PDCCH to PHICH signaling, then adequate PHICH resources for multiple carriers are provided, but PDCCH signaling capacity is reduced
Solution Approach 1:
The patent implements dynamic resource allocation where CCEs can be flexibly assigned to either PDCCH or PHICH functions based on system needs. This dynamic switching allows the system to adapt between different operational modes (single carrier vs. multiple carriers), resolving the contradiction between PHICH resource availability and PDCCH signaling capacity.
Solution Approach 2:
The patent segments the control channel resources by introducing separate PHICH resource allocation mechanisms alongside PDCCH. This segmentation allows independent optimization of both functions, enabling adequate PHICH resources for multiple carriers while maintaining PDCCH capacity through alternative allocation methods.
3Device complexity
If a single downlink carrier handles acknowledgment for multiple uplink carriers, then system complexity is reduced, but the downlink carrier lacks sufficient acknowledgment resources
Solution Approach 1:
The patent makes the downlink carrier universal by enabling it to handle acknowledgment for multiple uplink carriers through CCE-based PHICH signaling. This multi-functional capability allows a single downlink carrier to serve multiple purposes, maintaining low system complexity while providing sufficient acknowledgment resources through the expanded CCE utilization.
Data Source
AI summary
A downlink subframe on a single downlink carrier supports physical layer acknowledgment signaling for multiple physical uplink shared channel (PUSCH) transmissions. The physical layer acknowledgement signaling may take the form of physical hybrid ARQ indicator channel (PHICH) signaling. A base unit reserves resource elements groups (REGs) for default PHICH signaling of default PUSCH transmissions. The base unit reserves control channel elements (CCEs) for physical downlink control channel (PDCCH) signaling. A CCE contains multiple interleaved REGs. The base unit takes any unreserved CCEs and maps those CCEs for physical layer acknowledgement signaling of additional PUSCH transmissions.