ePDCCH eCCE Indexing for Interference Coordination
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Solution Overview
Problem
The existing PDCCH design in LTE systems, which relies on cell-specific reference signals, limits the capacity and efficiency of wireless communication networks, especially in heterogeneous networks with multiple transmission nodes, and fails to fully exploit cell splitting gains and interference coordination.
Innovation Solution
The implementation of an enhanced physical downlink control channel (ePDCCH) with localized and distributed enhanced control channel elements (eCCEs), where logical indexing is performed based on aggregation levels, and the ratio of localized to distributed eCCEs is determined to optimize resource allocation and interference coordination, allowing for UE-specific reference signals and increased capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell-specific reference signals are used for PDCCH demodulation, then the system maintains backward compatibility and simple reference signal structure, but the network capacity and efficiency are limited, especially in heterogeneous networks
Solution Approach 1:
The patent segments the reference signal structure by introducing two distinct types: cell-specific reference signals (CRS) for legacy PDCCH support and user-specific reference signals (UE-RS) for enhanced ePDCCH. This segmentation allows the system to maintain backward compatibility with CRS while simultaneously enabling advanced features through UE-RS, thereby increasing network capacity without compromising existing functionality
Solution Approach 2:
The patent introduces a new dimension to the reference signal architecture by adding user-specific reference signals that are specifically designed for enhanced physical downlink control channels. This dimensional expansion allows the system to support heterogeneous networks and advanced techniques like MU-MIMO, transforming the single-dimension CRS structure into a multi-dimensional reference signal framework
2Productivity
If localized eCCEs are used for ePDCCH, then resource allocation efficiency is improved, but interference coordination becomes more challenging in heterogeneous networks
Solution Approach 1:
The patent applies local quality by implementing both localized eCCEs for resource allocation efficiency and distributed eCCEs for interference coordination. Localized eCCEs concentrate control channel elements in specific resource blocks to improve resource utilization, while distributed eCCEs spread them across multiple resource blocks to reduce interference. The system dynamically selects between these two modes based on local network conditions, optimizing both efficiency and interference management
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the system to switch between localized and distributed eCCE modes based on network conditions. This dynamic approach enables the system to optimize resource allocation efficiency when conditions permit, while automatically transitioning to interference-coordinated distributed modes when needed, making the reference signal structure adaptable to heterogeneous network environments
3Object-affected harmful factors
If distributed eCCEs are used for ePDCCH, then interference coordination is improved, but resource allocation efficiency decreases
Solution Approach 1:
The patent applies local quality by implementing both localized eCCEs for resource allocation efficiency and distributed eCCEs for interference coordination. Localized eCCEs concentrate control channel elements in specific resource blocks to improve resource utilization, while distributed eCCEs spread them across multiple resource blocks to reduce interference. The system dynamically selects between these two modes based on local network conditions, optimizing both efficiency and interference management
Solution Approach 2:
The patent introduces dynamic adaptability by allowing the system to switch between localized and distributed eCCE modes based on network conditions. This dynamic approach enables the system to optimize resource allocation efficiency when conditions permit, while automatically transitioning to interference-coordinated distributed modes when needed, making the reference signal structure adaptable to heterogeneous network environments
4Device complexity
If legacy PDCCH design is maintained, then system complexity is kept low, but advanced techniques like MU-MIMO and HetNets cannot be fully utilized
Solution Approach 1:
The patent merges legacy PDCCH functionality with enhanced ePDCCH capabilities by maintaining cell-specific reference signals for backward compatibility while introducing user-specific reference signals for advanced techniques. This merging allows the system to support both traditional and advanced features simultaneously, enabling MU-MIMO and heterogeneous networks without requiring a complete system redesign
Solution Approach 2:
The patent creates a universal reference signal framework where cell-specific reference signals serve legacy PDCCH requirements while user-specific reference signals enable enhanced ePDCCH functionality. This multi-functional design allows the same physical downlink channel structure to support both traditional and advanced techniques, increasing system versatility without proportionally increasing complexity
Data Source
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AI summary
Technology for performing indexing on localized enhanced control channel elements (eCCEs) and distributed eCCEs for ePDCCH in a radio frame is disclosed. One method comprises indexing localized eCCEs and distributed eCCEs independently based an aggregation level for an enhanced physical downlink control channel (ePDCCH) transmission. For example, physical indexes of the localized eCCEs may be indexed in frequency increasing order while the indexing is aggregation level specifically mapped to physical indexes. For distributed eCCEs, the logical indexing may further take inter-cell interference (ICIC) coordinate region into consideration. The eCCE indexes belonging to the search space for a given aggregation level (AGGL) may distribute across different ICIC coordinate regions. Further, an AGGL specific global logical indexing may be applied to localized eCCEs and distributed eCCEs with the logical indexes for localized eCCEs and distributed eCCEs interleaved with each other. The ICIC region may also be considered in the global indexing. The AGGL specific eCCE indexing can be used for ePDCCH assignment and blind decoding and/or resource allocation for ePDCCH. The physical eCCE indexes can be used for implicit index derivation for a physical uplink control channel (PUCCH).