Carrier Aggregation Control Channel Resource Determination
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Solution Overview
Problem
In carrier aggregation systems, the limited size of the search space for physical downlink control channels (PDCCHs) leads to a high blocking probability in scheduling, as user equipment (UE) needs to monitor multiple component carriers, causing inefficiencies in control channel resource allocation.
Innovation Solution
The method determines temporary candidate control channel resources by mapping relationships between component carriers for data and control channels, allowing for different resource configurations based on the number of downlink control information bits, thereby enlarging the search space and reducing blocking probabilities without increasing blind decodings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the search space size is limited as defined in the related art, then the device complexity is reduced, but the blocking probability of PDCCH scheduling increases
Solution Approach 1:
The patent extends the search space from a two-dimensional space (aggregation level × CCE index) to a three-dimensional space by introducing the component carrier dimension. UEs now monitor PDCCH candidates across multiple component carriers, each with its own search space. This dimensional expansion increases the total number of available PDCCH candidates without increasing the complexity within each individual search space, thereby reducing blocking probability while maintaining manageable device complexity.
Solution Approach 2:
The patent divides the overall search space into multiple separate search spaces, each associated with a specific component carrier. Instead of having one large search space, the system segments the search space into smaller units distributed across different component carriers. This segmentation allows UEs to monitor multiple smaller search spaces in parallel, increasing the total capacity for PDCCH scheduling while keeping each individual search space simple and manageable.
2Productivity
If multiple component carriers are used for data channels, then the data transmission capacity is improved, but the blocking probability of control channel scheduling increases
Solution Approach 1:
The patent makes component carriers multi-functional by enabling them to carry both data channels (PDSCH/PUSCH) and control channels (PDCCH). Each component carrier can independently schedule data transmissions and carry control information, eliminating the bottleneck where a limited number of control carriers had to serve multiple data carriers. This multi-functionality ensures that data transmission capacity scales with the number of component carriers while control channel capacity also scales accordingly.
Solution Approach 2:
The patent introduces the component carrier dimension to the control channel resource allocation, transforming the control channel search space from a fixed two-dimensional structure to a scalable three-dimensional structure. This allows the control channel capacity to scale proportionally with the number of component carriers used for data transmission, maintaining reliable scheduling even as data transmission capacity increases through carrier aggregation.
3Reliability
If the search space is enlarged to reduce blocking probability, then the scheduling reliability is improved, but the number of blind decodings increases
Solution Approach 1:
The patent segments the enlarged search space into multiple smaller search spaces distributed across different component carriers. Instead of requiring UEs to perform blind decodings across one large search space, the system divides the candidates into smaller groups on different carriers. This segmentation reduces the computational burden per carrier while maintaining the total number of candidates needed for reliable scheduling, as UEs can process multiple smaller search spaces in parallel.
Solution Approach 2:
The patent distributes PDCCH candidates across the component carrier dimension, transforming the blind decoding problem from a concentrated two-dimensional search to a distributed three-dimensional search. This distribution allows UEs to parallelize the blind decoding process across multiple carriers, reducing the peak computational load and making the enlarged search space more manageable in terms of device complexity and processing requirements.
Data Source
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AI summary
A method and a device for determining a search space and for determining candidate control channel resources are provided in present invention. The method for determining the search space includes: determining the number of downlink control information bits of each type of control channel currently required to be monitored by a User Equipment (UE); determining a temporary search space corresponding to each type of control channel currently required to be monitored by the UE according to a mapping relationship between a component carrier for carrying a data channel and a component carrier for carrying a control channel, where the mapping relationship is currently used by the UE; and determining that an actual search space corresponding to a selected type of control channel is all or a part of CCEs of a union of temporary search spaces corresponding to all or a part of control channels with the same number of the downlink control information bits, for control channels that are currently required to be monitored by the UE and are of a same CCE aggregation level, when the DCI bit number of one or more other control channels is the same as the DCI bit number of the selected type of control channel. By using the solution, in a carrier aggregation system, the blocking probability of PDCCH scheduling can be decreased.