LTE-A PDCCH Search Space Design for Multi-Carrier Scheduling
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Solution Overview
Problem
In LTE-A multi-carrier operation, the existing PDCCH search space design faces challenges with increased 'crowdedness' due to multiple component carriers, leading to difficulties in supporting a large number of PDCCHs efficiently, especially when UE-specific and common search spaces overlap, limiting decoding candidates and affecting scheduling flexibility.
Innovation Solution
The proposed solution involves increasing the number of PDCCH candidates and/or UE-specific search spaces based on the number of carriers, with options including linearly increasing decoding candidates per search space or adding more search spaces, and using an offset-based design to optimize blind detection complexity and flexibility in scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of PDCCH candidates is increased to support multiple component carriers, then the scheduling flexibility and carrier accommodation capability are improved, but the blind detection complexity and processing overhead increase
Solution Approach 1:
The patent divides the PDCCH search space into multiple segments (first search space and second search space) with different candidate sets. The first search space contains candidates for the first component carrier, while the second search space contains candidates for the second component carrier. This segmentation allows the UE to process carriers independently, reducing the complexity of handling all carriers simultaneously while maintaining the ability to support multiple carriers.
Solution Approach 2:
The patent applies different PDCCH candidate configurations to different search spaces based on their specific requirements. Each search space has a tailored candidate set optimized for its specific component carrier, allowing each region to be processed with appropriate local complexity rather than uniformly high complexity across all carriers.
2Adaptability or versatility
If multiple search spaces are added to support cross-carrier scheduling, then the scheduling flexibility is improved, but the control signal overhead and processing load increase
Solution Approach 1:
The patent designs search spaces that can serve multiple purposes. The search space configuration allows a single structure to support both same-carrier and cross-carrier scheduling operations, as well as both UE-specific and common control information. This multi-functionality reduces the need for completely separate control channels for each function, thereby limiting the increase in overhead while maintaining scheduling flexibility.
3Productivity
If the PDCCH search space is expanded to accommodate more component carriers, then the system capacity is improved, but the search space crowdedness and interference increase
Solution Approach 1:
The patent segments the PDCCH search space into distinct regions (first search space for first component carrier, second search space for second component carrier) to reduce interference and crowdedness. By separating the search spaces, the patent prevents different component carriers from competing for the same search space resources, thereby reducing search space crowdedness while maintaining the ability to support multiple carriers and improve system capacity.
Data Source
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AI summary
A method, an apparatus, and a computer program product are provided in which a configuration for utilizing a plurality of carriers is received. In addition, a set of PDCCH candidates on a carrier of the plurality of carriers are determined for obtaining DCI for at least one carrier of the plurality of carriers. The number of PDCCH candidates is a function of a number of carriers of the at least one carrier.