E-PDCCH Search Space Allocation for Interference Coordination
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Solution Overview
Problem
Current wireless communication systems face limitations in expanding the control region for Physical Downlink Control Channels (PDCCHs) due to resource constraints, which affects DL throughput and interferes with interference coordination in the frequency domain, especially in scenarios like cell aggregation and multi-UE spatial multiplexing.
Innovation Solution
The solution involves defining methods and apparatus for user equipment (UE) to decode and search for both interleaved and non-interleaved Enhanced PDCCHs (E-PDCCHs) within the same subframe, allowing for flexible allocation of physical resource blocks (PRBs) and Enhanced Control Channel Elements (E-CCEs) to enhance control channel capacity and interference coordination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the control region size is increased to accommodate more PDCCHs, then the control channel capacity is improved, but the downlink throughput is reduced due to increased overhead
Solution Approach 1:
The patent segments the control region into multiple search spaces (common search space and user-specific search spaces) and further divides candidate PDCCH locations into multiple hypotheses. This segmentation allows the system to efficiently manage control channel capacity by organizing PDCCH candidates in a structured manner, enabling more PDCCHs to be accommodated without linearly increasing overhead through the systematic allocation of control channel elements (CCEs) across different search spaces and aggregation levels.
2Reliability
If the PDCCH search process is made more comprehensive to cover all possible locations, then the reliability of PDCCH detection is improved, but the complexity of the search process increases
Solution Approach 1:
The patent implements a dynamic search process where the UE adaptively determines PDCCH candidate locations based on multiple hypotheses and search space configurations. The search process dynamically adjusts the number of candidates, aggregation levels, and search space assignments based on channel conditions and scheduling requirements. This dynamic approach maintains high detection reliability by covering multiple possible locations while managing complexity through structured hypothesis testing and configurable search spaces.
Solution Approach 2:
The patent employs partial action by limiting the search to a predefined set of candidate locations and hypotheses rather than exhaustively searching all possible PDCCH positions. The system configures a specific number of PDCCH candidates per search space and per aggregation level, creating a controlled subset of search locations. This partial search approach achieves sufficient detection reliability for practical systems while significantly reducing the computational complexity compared to a complete search of all possible PDCCH locations.
3Device complexity
If traditional PDCCH transmission methods are used, then the system structure is simple, but interference coordination in the frequency domain is limited
Solution Approach 1:
The patent extends the traditional PDCCH structure by introducing multiple dimensions of search space organization: common search space versus user-specific search spaces, different aggregation levels (1, 2, 4, 8 CCEs), and multiple hypothesis candidates. This multi-dimensional structure enables frequency domain interference coordination by allowing different UEs to be assigned to different search spaces and CCE allocations, providing versatility in resource allocation while maintaining the fundamental PDCCH transmission framework.
Data Source
AI summary
A method for a user equipment (UE) to determine locations for M candidate physical downlink control channels (PDCCHs) in a set of N physical resource blocks (PRBs) in a transmission time interval (TTI) is provided. The method includes determining a location for each of M candidate PDCCHs in a different PRB if N is greater than or equal to M and determining a location for each of N candidate PDCCHs in a different PRB and determining a location for each of remaining M−N candidate PDCCHs in a different PRB if M is greater than N and 2N is greater than or equal to M.