Common Search Space Design for Coverage Enhancement in Wireless
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Solution Overview
Problem
Wireless communication systems face limitations in coverage due to a limited signal-to-interference ratio (SINR) and number of scheduling grants in the physical downlink control channel (PDCCH), particularly in MulteFire systems, where the common search space has restricted resources, affecting the transmission of paging information, system information, and random access procedures.
Innovation Solution
The implementation of an enhanced physical downlink control channel (ePDCCH) with higher aggregation levels and additional common search spaces, allowing for improved coverage and increased scheduling grants by scrambling demodulation reference signals with cell ID and allocating specific resource blocks for frame structure signaling and grant scheduling, as signaled within the master information block (MIB).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the common search space uses limited resources for PDCCH information, then the system maintains simplicity in resource allocation, but the coverage is limited and the number of scheduling grants is restricted
Solution Approach 1:
The patent divides the common search space into multiple segments or layers, allowing different aggregation levels (e.g., AL4, AL8, AL16, AL32) to be used for different purposes. This segmentation enables the system to maintain a compact base structure while extending coverage through hierarchical resource organization, resolving the contradiction between limited resources and coverage requirements.
Solution Approach 2:
The patent introduces additional dimensions to the resource allocation by implementing multiple common search spaces with different aggregation levels and configurations. Instead of expanding a single search space, the system adds dimensional layers (different ALs, different search space sets) to increase scheduling grant capacity and coverage without proportionally increasing base resource consumption.
2Productivity
If the PDCCH uses standard aggregation levels, then the resource allocation remains efficient, but the signal-to-interference ratio is insufficient for coverage enhancement
Solution Approach 1:
The patent dynamically changes the aggregation level parameter of the PDCCH based on coverage requirements and channel conditions. By allowing aggregation levels to be adjusted (e.g., from AL4 to AL32), the system can improve the signal-to-interference ratio when needed while maintaining efficient resource allocation under normal conditions, thus resolving the contradiction between efficiency and reliability.
Solution Approach 2:
The patent implements dynamic aggregation level selection where the PDCCH aggregation level is not fixed but can be adapted based on coverage enhancement needs, interference conditions, and traffic requirements. This dynamic approach allows the system to optimize the balance between resource efficiency and signal quality in real-time, resolving the static contradiction between efficiency and reliability.
3Reliability
If additional common search spaces are implemented for coverage enhancement, then the coverage and scheduling grants increase, but the system complexity increases
Solution Approach 1:
The patent designs the multiple common search spaces with unified structures and standardized procedures, allowing them to serve multiple functions simultaneously (coverage enhancement, scheduling, system information transmission). This multi-functionality approach reduces the need for separate specialized mechanisms, thereby limiting the increase in system complexity while achieving coverage enhancement goals.
Solution Approach 2:
The patent implements a nested structure where common search spaces with different aggregation levels are organized in a hierarchical manner, with higher aggregation levels providing coverage enhancement for UEs in poor signal conditions while lower aggregation levels serve UEs in better conditions. This nesting allows the system to manage multiple search spaces in an organized fashion, reducing the complexity overhead of handling multiple independent structures.
4Quantity of substance
If the common search space is expanded to accommodate more scheduling grants, then the number of supported UEs increases, but the resource consumption increases
Solution Approach 1:
The patent implements partial expansion of the common search space by introducing additional search space candidates and aggregation levels only where and when needed for coverage enhancement, rather than uniformly expanding all resources. This partial action approach allows the system to increase the number of scheduling grants for UEs requiring coverage enhancement while avoiding unnecessary resource consumption for UEs in good signal conditions.
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. A base station and user equipment (UE) may utilize an enhanced physical downlink control channel (ePDCCH) within a common search space to establish a MulteFire connection. The common search space may include a common PDCCH (C-PDCCH) and a MulteFire system information block (SIB-MF1) grant. The base station may define one or more common search spaces for the SIB-MF1 grants and C-PDCCH and signal the resource allocation for the common search spaces to the UE within a master information block (MIB). Each common search space may include a fixed set of control elements that the UE monitors for decoding the SIB-MF1 grants and C-PDCCH. In some cases, the base station may hardcode resources for the SIB-MF1 grants and C-PDCCH. Alternatively, the base station may signal the resources for each of the SIB-MF1 grants and C-PDCCH via reserved bits in the MIB.