5G PDCCH Design Using Mixed TDM and FDM Multiplexing
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Solution Overview
Problem
Current 5G network control channels, such as PDCCH, face limitations in capacity and flexibility due to limited resource allocation and interference issues, particularly in systems supporting carrier aggregation and machine-type communications.
Innovation Solution
A novel physical downlink control channel design that employs a mixed Time Division Multiplexing (TDM) and Frequency Division Multiplexing (FDM) mode, allowing for dynamic sub-band allocation and improved scheduling, which enhances processing time for the physical downlink shared channel and supports frequency-selective scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional PDCCH design with limited resource allocation is used, then device complexity is reduced, but control channel capacity is insufficient
Solution Approach 1:
The control channel is divided into multiple search spaces (common and UE-specific) with different aggregation levels, allowing flexible resource allocation across multiple PDCCH candidates. This segmentation enables the system to support more control channels by organizing them in a structured hierarchy rather than treating them as a monolithic resource pool.
Solution Approach 2:
The patent introduces a two-dimensional search space structure combining aggregation level (vertical dimension) and candidate index (horizontal dimension). This dimensional organization allows UEs to efficiently search through multiple PDCCH candidates with different resource allocations, significantly increasing control channel capacity while maintaining manageable complexity through systematic organization.
2Quantity of substance
If control channel occupies more resources, then control channel capacity increases, but processing time for physical downlink shared channel decreases
Solution Approach 1:
The search space configuration is made dynamic through higher-layer signaling, allowing the network to adjust the number of PDCCH candidates and aggregation levels based on traffic conditions. This dynamic adaptation enables the system to allocate more control channel resources when needed while preserving processing time for PDSCH during normal operation, resolving the time-capacity tradeoff.
Solution Approach 2:
The patent changes key parameters such as aggregation level, number of candidates, and search space size through RRC signaling. By dynamically adjusting these parameters, the system can increase control channel capacity in specific scenarios without permanently reducing the time available for PDSCH processing, thus balancing both requirements.
3Adaptability or versatility
If fixed resource allocation is used, then device complexity is reduced, but adaptability for different applications and services is limited
Solution Approach 1:
The search space design provides a universal framework that serves multiple functions: common control information, UE-specific scheduling, and dynamic sub-band allocation. By making the same PDCCH structure multi-functional through configurable search spaces, the system achieves high adaptability without requiring separate specialized channels for each application, thus managing complexity effectively.
4Reliability
If control channel uses centralized frequency allocation, then device complexity is reduced, but interference issues increase in carrier aggregation systems
Solution Approach 1:
The patent applies local quality by allowing different search spaces to be configured with different frequency locations and aggregation levels. This enables frequency-selective scheduling where control channels can be placed in less interfered frequency regions, improving reliability for specific UEs or services without requiring complete redistribution of all control channel resources, thus managing complexity locally rather than globally.
Data Source
AI summary
Disclosed herein are apparatuses, systems, and methods using or implementing a control channel (PDCCH) design. The PDCCH can occupy an initial number of OFDM symbols of a downlink subframe, while occupying less than the full system bandwidth. The PDCCH can be time division multiplexed (TDM) with a shared channel (PDSCH) or frequency division multiplexed (FDM) with a PDSCH. The PDCCH can further be multiplexed with another PDCCH in a contiguous or non-contiguous region. Resources allocated to the PDCCH can overlap or partially overlap resources allocated to the PDSCH. An Evolved Node-B (eNB) can provide configuration information for the PDCCH design in Radio Resource Control (RRC) signaling to a user equipment (UE), or through use of a Master Information Block (MIB) or System Information Block (SIB).