ePDCCH Resource Allocation for High-Capacity Downlink Control
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Solution Overview
Problem
Conventional cellular mobile communication systems face increasing demands for larger capacity of control channels due to technologies like Multi-user Multiple Input Multiple Output (MU-MIMO), Carrier Aggregation, and Coordinated Multipoint (COMP), necessitating a new control channel design.
Innovation Solution
The method involves dividing the Physical Downlink Control Channel (PDCCH) area from the Physical Downlink Shared Channel (PDSCH) area to create an enhanced Physical Downlink Control Channel (ePDCCH) resource, which can be transmitted through one or both slots of a subframe, using PRBs, UE-specific PRBs, and eCCEs, and is signaled through System Information or RRC signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If control information is transmitted using conventional PDCCH area with one to three OFDM symbols, then the transmission method is simple and structure is maintained, but the control channel capacity is insufficient for MU-MIMO and heterogeneous network environments
Solution Approach 1:
The patent divides the downlink channel into separate PDCCH area and PDSCH area, with the PDCCH area further segmented into multiple ePDCCH regions. This segmentation allows control information to be distributed across multiple resource blocks and OFDM symbols, significantly increasing control channel capacity while maintaining organized structure through defined search spaces and resource allocation rules.
Solution Approach 2:
The patent extends control channel transmission from the time dimension (one to three OFDM symbols) to include frequency dimension resources (multiple resource blocks). By allocating ePDCCH across multiple PRBs and OFDM symbols within the PDCCH area, the control channel capacity is expanded without fundamentally changing the OFDM frame structure.
2Quantity of substance
If ePDCCH resource is allocated through PDSCH area using multiple PRBs and eCCEs, then control information capacity is increased, but resource allocation complexity and signaling overhead increase
Solution Approach 1:
The patent implements self-service mechanisms where the terminal autonomously determines ePDCCH resources by searching predefined search spaces (common and UE-specific) without requiring explicit resource allocation signaling. The base station configures search space parameters through higher-layer signaling, but actual resource selection is performed automatically by the terminal based on its UE ID and configured parameters, reducing signaling overhead.
Solution Approach 2:
The patent uses parameter changes to manage resource allocation complexity. By configuring search space parameters (number of PRBs, OFDM symbols, resource block offsets) through higher-layer signaling and allowing dynamic adjustment based on traffic conditions and UE requirements, the system can adapt control channel capacity without redesigning the entire resource allocation mechanism.
3Adaptability or versatility
If PDCCH area is divided from PDSCH area to create ePDCCH, then control channel capacity is enhanced for MU-MIMO and Carrier Aggregation, but system complexity increases
Solution Approach 1:
The patent creates a universal ePDCCH structure that can serve multiple functions: supporting MU-MIMO through spatial multiplexing, enabling Carrier Aggregation via cross-carrier scheduling, and providing services for heterogeneous networks. The same ePDCCH resource allocation mechanism and search space structure are used across different scenarios, reducing the need for separate specialized structures for each use case.
Data Source
AI summary
The method for transmitting control information in a mobile communication system includes: determining a control channel resource for transmitting control information by means of the data channel region; and transmitting the control information using the determined control channel resource. A capacity for control information, which increases for multiple user multiple-input multiple-out (MIMOs) in a heterogeneous network environment, for heterogeneous network interference control using carrier aggregation, for frequent use of a multicast-broadcast single frequency network (MBSFN) subframe, and for a COMP transmission control, may be satisfied. Further, an adaptive resource allocation based on a requested capacity for control information may be enabled, and the efficient utilization of resources may also be enabled.