EPDCCH-CSS Cell Detection in Small Cells Without PDCCH
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Solution Overview
Problem
In small cell networks using the New Carrier Type (NCT) configuration, idle mode UEs cannot recognize the small cell or receive downlink control information (DCIs) due to the absence of a physical downlink control channel (PDCCH), necessitating a system that allows UEs to detect the EPDCCH-CSS without a UE-specific control signal and acquire resource allocation information.
Innovation Solution
A base station apparatus generates and transmits allocation information scrambled with its cell ID, along with a detection signal and control signals, to enable UEs to detect the EPDCCH-CSS and extract resource information, allowing them to recognize the small cell and receive DCIs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a small cell uses NCT configuration without PDCCH, then transmission power control and interference management are improved, but idle mode UEs cannot recognize the cell or receive DCIs
Solution Approach 1:
The patent introduces EPDCCH-CSS as an intermediary mechanism between the base station and idle mode UEs. This enhanced control channel search space acts as a mediator that enables cell detection and DCI reception without requiring traditional PDCCH, thus resolving the contradiction between NCT benefits and idle UE connectivity.
Solution Approach 2:
The patent implements preliminary configuration of EPDCCH-CSS with cell ID scrambling and resource allocation information before idle mode UEs need to access the network. This preliminary setup ensures that when idle UEs perform cell detection, they can acquire the necessary information to receive DCIs without requiring prior connection establishment.
2Device complexity
If EPDCCH-CSS is configured with limited resources, then device complexity is reduced, but cell detection accuracy and throughput are insufficient
Solution Approach 1:
The patent dynamically adjusts parameters such as the number of RBs allocated to EPDCCH-CSS and the scrambling code based on cell ID. By changing these parameters adaptively, the system achieves both manageable complexity and sufficient cell detection accuracy without requiring excessive resource allocation.
Solution Approach 2:
The patent applies different resource allocation strategies for different parts of the frequency spectrum. By locally optimizing the EPDCCH-CSS configuration in specific resource blocks, the system achieves high cell detection accuracy without uniformly increasing complexity across the entire spectrum.
3Reliability
If allocation information is scrambled with cell ID, then security and interference control are improved, but UE processing complexity increases
Solution Approach 1:
The patent enables idle mode UEs to autonomously perform cell detection and acquire allocation information using the cell ID scrambling mechanism. The UEs self-service by detecting the EPDCCH-CSS and extracting necessary information without requiring network assistance, thus achieving security benefits while managing processing complexity.
Data Source
AI summary
Disclosed is a base station apparatus which allows an idle mode UE, in a small cell using S-NCT, to recognize the small cell and to receive a DCI. The base station apparatus is configured to use a carrier configuration which has no region for mapping a PDCCH and in which an EPDCCH is mapped in a data region. The base station apparatus includes: master information generating section 101 configured to generate allocation information indicating a resource which forms a search space in the EPDCCH and being scrambled with a cell ID of the base station apparatus; and transmitting section 107 configured to transmit the allocation information, a detection signal indicating the cell ID, and a control signal assigned in the search space.