Flexible Search Space Configuration for Wireless Control Channels
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Solution Overview
Problem
Wireless communications systems face inefficiencies in scheduling and monitoring downlink control information due to limitations on the number of control channel elements (CCEs) and blind decoding attempts, leading to coexistence interference and resource underutilization in search spaces.
Innovation Solution
Implementing flexible search space configuration and overbooking handling by constructing nested search spaces, adding pseudo search space candidates, and dropping CCEs or search space candidates based on priority and blind decoding limits to efficiently utilize CCEs and minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base stations configure multiple search space candidates with different aggregation levels to improve control information reliability, then the reliability of control information transmission is improved, but the number of blind decoding attempts and CCE usage increases beyond system limits
Solution Approach 1:
The patent implements nested search spaces where a first search space is constructed within a second search space. The first search space contains search space candidates that are a subset of the second search space candidates. This nesting allows the system to maintain multiple aggregation levels for reliability while avoiding duplicate blind decoding attempts, as the nested structure ensures that candidates are shared rather than replicated across search spaces.
Solution Approach 2:
The patent segments the search space configuration into multiple hierarchical levels (first search space nested within second search space). Each search space is divided into aggregation levels, and the nesting creates a segmented structure where candidates at different levels are organized systematically. This segmentation allows the base station to manage blind decoding attempts and CCE usage by clearly defining which candidates belong to which search space level.
2Quantity of substance
If base stations increase the number of CCEs allocated to search spaces to accommodate more control information, then the capacity for control information transmission is improved, but coexistence interference between search spaces increases
Solution Approach 1:
By nesting the first search space within the second search space, the patent enables efficient CCE allocation where the nested structure naturally manages resource sharing. The first search space candidates are a subset of the second, meaning they share the same CCE resources rather than competing for separate allocations. This reduces coexistence interference while maintaining the total control information capacity through hierarchical organization.
Solution Approach 2:
The patent merges the resource allocation of nested search spaces by making the first search space candidates a subset of the second. This combining approach allows CCEs to serve multiple purposes across different search space levels, increasing overall control information capacity while reducing interference through unified resource management rather than separate allocations.
3Stability of the object's composition
If base stations strictly enforce CCE limits per bandwidth part to maintain system stability, then the stability and fairness of resource allocation is improved, but the utilization efficiency of CCEs decreases
Solution Approach 1:
The nested search space structure allows the system to maintain stability by organizing candidates hierarchically within defined limits, while improving utilization efficiency through the subset relationship. The first search space (nested) and second search space (parent) together utilize CCEs more efficiently than separate configurations, as the nesting enables shared resource usage without exceeding overall system limits, thus achieving both stability and productivity.
Data Source
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Figure 3A~3B
AI summary
Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a base station may transmit control information to a user equipment (UE) in search space candidates within a configured search space. To flexibly configure the search space, the base station may determine a reference aggregation level. The base station may add a number of pseudo search space candidates to the reference aggregation level such that the control channel element (CCE) footprint of the reference aggregation level can handle nesting all of the candidates for other aggregation levels. In some cases, the base station may overbook the search space past a CCE limit. The base station may implement an overbooking rule to determine search space candidates to drop from the configuration. The base station may transmit using the search space configuration, and the UE may monitor and decode information according to the configuration.