LTE-A Cross-Subframe ACK Resource Allocation
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Solution Overview
Problem
In wireless communication networks, acknowledgment resource collisions occur due to shared starting control channel elements (CCE) across different subframes, leading to interference and degraded performance in both downlink and uplink transmissions.
Innovation Solution
The method involves transmitting physical downlink control channels (PDCCHs) in different subframes to assign resources for physical downlink shared channel (PDSCH) transmissions, with the determination of acknowledgment resources dependent on the subframe in which the PDCCH was transmitted, to avoid collisions by using distinct CCE numbering or offsets across subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same starting CCE index is used for PDCCH transmissions in different subframes, then resource allocation is simplified, but acknowledgment resource collisions occur leading to degraded performance
Solution Approach 1:
The patent applies local quality by making the CCE numbering scheme subframe-specific. Each subframe has its own localized CCE numbering starting from a subframe-dependent offset, so that the same CCE index in different subframes refers to different physical resources. This resolves the contradiction by maintaining simple indexing logic locally within each subframe while ensuring global uniqueness across subframes, thereby preventing acknowledgment resource collisions without significantly increasing complexity.
Solution Approach 2:
The patent introduces a new dimension to the resource allocation by incorporating the subframe index into the CCE resource identification. Instead of using only the CCE index within a single subframe, the system now considers the combination of subframe number and CCE index, effectively moving from a 1D resource space to a 2D resource space. This dimensional expansion ensures unique resource allocation across multiple subframes while maintaining the simplicity of individual subframe processing.
2Adaptability or versatility
If cross-subframe resource allocation is implemented, then scheduling flexibility is improved, but acknowledgment resource determination becomes more complex
Solution Approach 1:
The patent changes the parameter used for acknowledgment resource determination from a static CCE-based indexing to a dynamic subframe-dependent CCE numbering. The starting offset for CCE numbering is changed based on the subframe index, which allows the system to maintain simple determination logic (using the same basic formula) while adapting to different subframes. This parameter change enables cross-subframe scheduling flexibility without significantly increasing the complexity of acknowledgment resource determination.
Data Source
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AI summary
A method, apparatus and computer-program thereof for acknowledgement transmissions under cross-subframe resource allocation are described, comprising : transmitting, in different subframes, physical downlink control channels (PDCCHs) assigning resources for a plurality of physical downlink shared channel (PDSCH) transmissions in a common subframe; and determining, for each PDSCH transmissions transmitted in the common subframe, resources for use in receiving an acknowledgement (ACK) of whether or not the PDSCH transmission was successfully received, wherein the determining is dependent, at least in part, on a subframe in which the PDCCH was transmitted.